chore: Add contributing guidelines (CONTRIBUTING.md) (#188)

* chore: Add contributing guidelines (CONTRIBUTING.md)

Add contributing guidelines (CONTRIBUTING.md) to the repo in order to define rules, standard and general guidelines for every future contributions and interactions in this project.

Addresses parts of #183

* style(CONTRIBUTING): Various wording improvements and typo fixes

* style(CONTRIBUTING): Remove trailing space

.github/PULL_REQUEST_TEMPLATE.md

@@ -16,10 +16,10 @@ Paste any relevant logs here (if you have some)
 
 <!-- If this pull request is fixing an opened bug report, paste the corresponding issue URL below -->
 
-Fixes "issue_URL"
+Fixes "issue_URL" (if any)
 
 ### Addressed feature request
 
 <!-- If this pull request is addressing an opened feature request, paste the corresponding issue URL below -->
 
-Closes "issue_URL"
+Closes "issue_URL" (if any)

CONTRIBUTING.md

@@ -0,0 +1,114 @@
+# Contributing
+
+Thank you for considering contributing to [Arch-Update](https://github.com/Antiz96/arch-update)!
+
+With the exception of the [general rules](#general-rules), which **must** be acknowledged and applied in any contribution/interaction in this project, these guidelines represents an ideal target & standards that I would like this project to follow but may not all be **strictly** enforced (depending on the situation).
+
+Please, don't refrain yourself from contributing if you feel that your contribution may not entirely follow these guidelines (or if you're struggling applying some of them). I value your contribution more than the strict application of these guidelines!
+
+## Table of contents
+
+- [General rules](#general-rules)
+- [Open an issue](#open-an-issue)
+- [Open a pull request](#open-a-pull-request)
+- [Donations](#donations)
+- [Thank you](#thank-you)
+
+## General rules
+
+These general rules apply to **every** contributions (whatever the type). They should **always** be acknowledged and **strictly** followed in any circumstances:
+
+Basic common sense applies to every contributions & discussions: stay polite and respectful, no flaming/trolling/spamming or any kind of discrimination/harassment, avoid controversial topics *(specifically if it has nothing to do with this project whatsoever)*, etc...
+
+Use English as much as possible for contributions & discussions. If required, I can also speak French, but it's important that contributions & discussions remain intelligible to most people.
+
+Arch-Update is developed and tested specifically with *vanilla* Arch Linux in mind. That doesn't mean that Arch-Update won't work with other Arch based distributions (e.g. EndeavourOS,  CachyOS, Garuda...), but keep in mind that such distributions are supported at a "best effort" level. In other words, I'll try my best to keep Arch-Update compatible with derivatives distributions, but there's no guarantee that Arch-Update (or parts of it) will continuously work properly on said distributions.
+
+## Open an issue
+
+Before [opening an issue](https://github.com/Antiz96/arch-update/issues/new/choose), verify that there isn't one already open on the same (or a similar) subject.
+
+Make sure to use the correct type for your issue (`Bug Report` or `Feature Request`) and to provide the requested information. If you have a doubt about which one is the most appropriate for your issue (or if you think that none of these types apply to your issue), feel free to use the general `Other` type.
+
+Providing as much details as possible in your issue will ease its processing.
+
+## Open a pull request
+
+Read the following sub-chapter before opening a pull request and make sure to provide the information requested in the [pull request template](https://github.com/Antiz96/arch-update/blob/main/.github/PULL_REQUEST_TEMPLATE.md).
+
+### Open an issue first
+
+Apart from trivial changes (like simple typo fixes), it is advised to first [open an issue](#open-an-issue) to expose and discuss your changes, verify its feasibility/necessity and agree on the specifications.
+
+### Coding style
+
+When submitting code changes, try to respect the coding style and the overall way things work as much as possible.  
+For instance, for the main bash script:
+
+- Stick to bash syntax
+- Variables should use the `"${var}"` format
+- Use the `{main,info,ask,warning,error}_msg` functions to print messages
+- Use `"$(eval_gettext "string")"` for any string chain that should be included in translations
+- [...]
+
+Bash code is checked with [shellcheck](https://www.shellcheck.net/).  
+Python code is checked with [pylint](https://github.com/pylint-dev/pylint).  
+Markdown syntax is checked with [markdownlint](https://github.com/markdownlint/markdownlint).
+
+### Commit message format
+
+Commits must follow the [conventional commits](https://www.conventionalcommits.org/en/v1.0.0/) specification.
+
+This project uses the following commit types:
+
+- chore: for internal/miscellaneous changes
+- feat: for new features (or improvements/additions to existing features)
+- fix: for bug fixes
+- doc: for documentation only changes
+- style: For changes that do not affect the meaning of the code (white-space, formatting, typo fixes, etc...)
+
+An optional scope can be provided to the commit type if relevant (for instance when a change is specific to precise part of the project), like so: `type(scope): commit message`.  
+If a commit introduces a breaking change, its type must contain a `!` (e.g. `feat!: commit message`) and/or a `BREAKING CHANGE:` mention should be added at the end of your commit message (e.g. `BREAKING CHANGE: description of the breaking change`).
+
+Here are a few examples of the expected commit format:
+
+```text
+feat(systray): Add a right click menu to the systray applet
+
+Add a right click menu to the systray applet containing two entries:
+One to run Arch-Update and one to "exit" (close) the systray applet
+
+Closes https://github.com/Antiz96/arch-update/issues/163
+```
+
+```text
+fix: Improve parsing on Flatpak cli output to avoid false positives
+
+The current parsing of the Flatpak cli output when looking for pending Flatpak updates is subject to false positives.
+This commit makes it more robust to avoid such issues.
+
+Fixes https://github.com/Antiz96/arch-update/issues/103
+```
+
+```text
+doc(man): Add the -l/--list option to man pages
+
+The recently introduced -l/--list option was missing from the man page
+```
+
+```text
+style: Typo fixes in README and man pages
+```
+
+### License
+
+By contributing to this project, you agree that your contributions will be licensed under the [GPL-3.0 license](https://github.com/Antiz96/arch-update/blob/main/LICENSE) (or any later version of this license).
+
+## Donations
+
+You can also support this project development (and my work in general) by making a small donation via my [GitHub sponsor page](https://github.com/sponsors/Antiz96).
+
+## Thank you
+
+Once again, thank you for considering contributing to Arch-Update!  
+I'd also like to thank everyone that already opened issues, feature requests, pull requests or contributed to Arch-Update in any other way! :heart:

README-fr.md

@@ -14,6 +14,7 @@
 - [Documentation](#documentation)
 - [Trucs et astuces](#trucs-et-astuces)
 - [Contribuer](#contribuer)
+- [Licence](#licence)
 
 ## Description
 
@@ -260,5 +261,8 @@ Alternativement, vous pouvez créer un lien symbolique de votre émulateur de te
 
 ## Contribuer
 
-Vous pouvez soulever vos problèmes, commentaires et suggestions dans l'onglet [Issues](https://github.com/Antiz96/arch-update/issues).  
-Les [Pull requests](https://github.com/Antiz96/arch-update/pulls) sont également les bienvenues !
+Veuillez lire le [guide de contribution](https://github.com/Antiz96/arch-update/blob/main/CONTRIBUTING.md).
+
+## Licence
+
+Arch-Update est sous [licence GPL-3.0](https://github.com/Antiz96/arch-update/blob/main/LICENSE) (ou toute version ultérieure de cette licence).

README.md

@@ -14,6 +14,7 @@
 - [Documentation](#documentation)
 - [Tips and tricks](#tips-and-tricks)
 - [Contributing](#contributing)
+- [License](#license)
 
 ## Description
 
@@ -260,5 +261,8 @@ Alternatively, you can create a symlink for your terminal emulator that points t
 
 ## Contributing
 
-You can raise your issues, feedbacks and suggestions in the [issues tab](https://github.com/Antiz96/arch-update/issues).  
-[Pull requests](https://github.com/Antiz96/arch-update/pulls) are welcomed as well!
+Please, read the [contributing guidelines](https://github.com/Antiz96/arch-update/blob/main/CONTRIBUTING.md).
+
+## License
+
+Arch-Update is licensed under the [GPL-3.0 license](https://github.com/Antiz96/arch-update/blob/main/LICENSE) (or any later version of that license).