📝 Update Contributing Guide (#24320)

.github/contributing.md

 
 We have a Message Board and a Facebook group where our knowledgable user community can provide helpful advice if you have questions.
 
-* [Marlin RepRap forum](https://reprap.org/forum/list.php?415)
-* [MarlinFirmware on Facebook](https://www.facebook.com/groups/1049718498464482/)
+- [Marlin Documentation](https://marlinfw.org) - Official Marlin documentation
+- Facebook Group ["Marlin Firmware"](https://www.facebook.com/groups/1049718498464482/)
+- RepRap.org [Marlin Forum](https://forums.reprap.org/list.php?415)
+- Facebook Group ["Marlin Firmware for 3D Printers"](https://www.facebook.com/groups/3Dtechtalk/)
+- [Marlin Configuration](https://www.youtube.com/results?search_query=marlin+configuration) on YouTube
 
 If chat is more your speed, you can join the MarlinFirmware Discord server:
 

README.md

  - Scott Lahteine [[@thinkyhead](https://github.com/thinkyhead)] - USA - Project Maintainer   [💸 Donate](https://www.thinkyhead.com/donate-to-marlin)
  - Roxanne Neufeld [[@Roxy-3D](https://github.com/Roxy-3D)] - USA
  - Keith Bennett [[@thisiskeithb](https://github.com/thisiskeithb)] - USA   [💸 Donate](https://github.com/sponsors/thisiskeithb)
- - Peter Ellens [[@ellensp](https://github.com/ellensp)] - New Zealand
+ - Peter Ellens [[@ellensp](https://github.com/ellensp)] - New Zealand    [💸 Donate](https://ko-fi.com/ellensp)
  - Victor Oliveira [[@rhapsodyv](https://github.com/rhapsodyv)] - Brazil
  - Chris Pepper [[@p3p](https://github.com/p3p)] - UK
  - Jason Smith [[@sjasonsmith](https://github.com/sjasonsmith)] - USA