Improve CONTRIBUTING.md

 - add links to the community forum
 - remove references to the mailing list (as suggested by Riya)
 - clarify and emphasize why bumping is annoying

Closes #5261
//FREEBIE

CONTRIBUTING.md

@@ -28,13 +28,15 @@ Please do not submit issues or pull requests for translation fixes. Anyone can u
 
 ### Issue tracker is for bugs
 The main purpose of this issue tracker is to track bugs for the Android client. Relevant, concise and to the point comments that help to solve the issue are very welcome.
+
 ##### Send support questions to support
 Please do **not** ask support questions at the issue tracker. We want to help you using Signal and we have created our support system just for that. You can reach support by sending email to support@whispersystems.org or by going to our [Support Center](http://support.whispersystems.org). You can also search for existing troubleshooting articles at the [Support Center](http://support.whispersystems.org).
+
 ##### Not a discussion forum
-Please do **not** use this issue tracker as a discussion forum. Discussion related to the bug in question should of course go to the issue itself. However general ideas about the application, design, security, goals etc. should go to the [mailing list](https://lists.riseup.net/www/info/whispersystems) instead.
+Please do **not** use this issue tracker as a discussion forum. Discussion related to the bug in question should of course go to the issue itself. However other discussion should take place at the [community forum](https://whispersystems.discoursehosting.net). You can use that forum to discuss any Signal related topics or to just hang out with your fellow users.
 
 ### Don't bump issues
-Unfortunately :+1:s, _me toos_ and asking for updates don't help solving issues. They just generate ever more notifications for the developers to wade through, so please refrain yourself from posting them. However if you have relevant new information to add to the issue then please don't shy away from commenting.
+Every time someone comments on an issue, GitHub sends email to [everyone who is watching](https://github.com/WhisperSystems/Signal-Android/watchers) the repository (currently around 500 people). Thus bumping issues with :+1:s, _me toos_ or asking for updates just generate unnecessary email notifications. Moreover bumping an issue does not help solving it. Please be respectful to everyone's time and try to only comment when you have relevant new information to add.
 
 ### Open issues
 
@@ -59,7 +61,7 @@ Before submitting a pull request please check that your code adheres to the [Cod
 Please do not submit pull requests that are still a work in progress. Pull requests should be ready for a merge when you submit them. Also please do not submit pull requests that you have not tested.
 
 ### Smaller is better
-Please do not try to change too much at once. Big changes are less likely to be merged. If you are a first time contributor start with small and simple PRs to get to know the codebase. If your PR requires huge changes to the codebase please ask in the [mailing list](https://lists.riseup.net/www/info/whispersystems) first to check if the idea is viable.
+Please do not try to change too much at once. Big changes are less likely to be merged. If you are a first time contributor start with small and simple PRs to get to know the codebase.
 
 ### Merging can sometimes take a while
 If your pull request follows all the advice above but still has not been merged it usually means the developers haven't simply had the time to review it yet. We understand that this might feel frustrating. We are sorry!
@@ -72,7 +74,7 @@ Accepted pull requests will be rewarded with Bitcoins! After your pull request h
 Any one can help by
 - advising new people about the guidelines of this project
  - redirecting support questions to support@whispersystems.org and the [support site](http://support.whispersystems.org)
- - redirecting relevant discussions to the [mailing list](https://lists.riseup.net/www/info/whispersystems)
+ - redirecting non-bug related discussions to the [community forum](https://whispersystems.discoursehosting.net)
 - improving documentation at the [wiki](https://github.com/WhisperSystems/Signal-Android/wiki)
 - [translating](https://www.transifex.com/projects/p/signal-android/)
 - finding and marking duplicate issues
@@ -80,7 +82,7 @@ Any one can help by
 - finding solutions to open issues and posting relevant findings as comments
 - submitting pull requests
 - testing other people's pull requests
-- spreading the joy of Signal to your friends
+- spreading the joy of Signal to your friends and family
 - donating money to our [BitHub](https://www.coinbase.com/checkouts/51dac699e660a4d773216b5ad94d6a0b) or through the [Freedom of the Press Foundation's donation page](https://freedom.press/bundle/encryption-tools-journalists)
 
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