Bug 1922478 - fix the docs where they point to github. r=android-reviewers,npoon

I started off fixing the link to the APK repos, then realised that most of the other links and info on the page was also wrong. So i have fixed various bits :)
I've gone for codetribute for the link to the good-first-bugs as it's a nice friendly ui and people can browse around other projects if they want to.

Differential Revision: https://phabricator.services.mozilla.com/D224456

Author: pollym

mobile/android/fenix/docs/Home.md

@@ -4,28 +4,28 @@ Firefox for Android is Mozilla's new browser for Android devices. Powered by Gec
 
 Firefox for Android is the first step in building a better mobile browser: one that’s faster, more secure and more independent than any mobile Firefox browser before it. It will combine the speed, privacy, control, and easy-to-use features you have come to expect from Firefox.
 
-*Don't see what you're looking for? Check out our shared docs: https://github.com/mozilla-mobile/shared-docs.*
+*Don't see what you're looking for? [Check out our shared docs](https://hg.mozilla.org/mozilla-central/file/tip/mobile/android/fenix/docs).*
 
 ## User support
 
-* Support articles: https://support.mozilla.org/en-US/products/mobile
-* Support forum: https://support.mozilla.org/en-US/questions/mobile
+* [Support articles](https://support.mozilla.org/en-US/products/mobile)
+* [Support forum](https://support.mozilla.org/en-US/questions/mobile)
 
 ## Download
 
 * Google Play: [Release](https://play.google.com/store/apps/details?id=org.mozilla.firefox)
 * Google Play: [Beta](https://play.google.com/store/apps/details?id=org.mozilla.firefox_beta)
 * Google Play: [Nightly](https://play.google.com/store/apps/details?id=org.mozilla.fenix)
-* Release APKs: https://github.com/mozilla-mobile/fenix/releases
-* Nightly APKs: https://firefox-ci-tc.services.mozilla.com/tasks/index/mobile.v2.fenix.nightly.latest
+* [Release APKs](https://archive.mozilla.org/pub/fenix/releases/)
+* [Nightly APKs](https://archive.mozilla.org/pub/fenix/nightly/)
 
 ## Contribute
 
 * [Contributing (Writing code, translating the app, testing the app)](https://github.com/mozilla-mobile/shared-docs/blob/master/android/CONTRIBUTING.md)
-* [List of good first issues for new contributors](https://github.com/mozilla-mobile/fenix/issues?utf8=%E2%9C%93&q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22+)
+* [List of good first issues for new contributors](https://codetribute.mozilla.org/projects/fenix?tag%3Dgood-first-bug)
 * [Mozilla Community Participation Guidelines](https://www.mozilla.org/en-US/about/governance/policies/participation/)
 
 ## Communication
 * External: [#fenix](https://chat.mozilla.org/#/room/#fenix:mozilla.org) on [Element](https://wiki.mozilla.org/Matrix)
 * External: [Firefox on Android discourse](https://discourse.mozilla.org/c/firefox-android/468)
-* Internal: Find us on slack #fenix-team
+* Internal: Find us on slack #mobile-android-team