Update build-instructions.md to use code tags

Update build-instructions.md to make (more) use of code tags

docs/software/build-instructions.md

@@ -6,10 +6,10 @@ in these instructions I describe use of their command line tool.
 1. Purchase a suitable radio (see above)
 2. Install [PlatformIO](https://platformio.org/platformio-ide)
 3. Download this git repo and cd into it
-4. Run "git submodule update --init --recursive" to pull in dependencies this project needs.
-5. If you are outside the USA, edit [platformio.ini](/platformio.ini) to set the correct frequency range for your country. The line you need to change starts with "hw_version" and instructions are provided above that line. Options are provided for EU433, EU835, CN, JP and US. Pull-requests eagerly accepted for other countries.
+4. Run `git submodule update --init --recursive` to pull in dependencies this project needs.
+5. If you are outside the USA, edit [platformio.ini](/platformio.ini) to set the correct frequency range for your country. The line you need to change starts with `hw_version` and instructions are provided above that line. Options are provided for `EU433`, `EU835`, `CN`, `JP` and `US` (default). Pull-requests eagerly accepted for other countries.
 6. Plug the radio into your USB port
-7. Type "pio run --environment XXX -t upload" (This command will fetch dependencies, build the project and install it on the board via USB). For XXX, use the board type you have (either tbeam, heltec, ttgo-lora32-v1, ttgo-lora32-v2).
+7. Type `pio run --environment XXX -t upload` (This command will fetch dependencies, build the project and install it on the board via USB). For XXX, use the board type you have (either `tbeam`, `heltec`, `ttgo-lora32-v1`, `ttgo-lora32-v2`).
 8. Platform IO also installs a very nice VisualStudio Code based IDE, see their [tutorial](https://docs.platformio.org/en/latest/tutorials/espressif32/arduino_debugging_unit_testing.html) if you'd like to use it.
 
 ## Decoding stack traces