The setting up editor docs should get updated

[hiddenblue]

https://docs.avaloniaui.net/docs/get-started/set-up-an-editor

the setting up docs is outdated. for example, the preview plugin for rider has already published for a long time

I wonder Whether we could update the part? The is important for freshman

May I could add some new introduction into it.

[thevortexcloud]

PRs are generally welcome. That said I am also not part of the Avalonia team, so it's really up to them.