Clean up the AUTHORS file (#6215)

AUTHORS.rst

-Erik Johnston <erik at matrix.org>
- * HS core
- * Federation API impl
+The following is an incomplete list of people outside the core team who have
+contributed to Synapse. It is no longer maintained: more recent contributions
+are listed in the `changelog <CHANGES.md>`_.
 
-Mark Haines <mark at matrix.org>
- * HS core
- * Crypto
- * Content repository
- * CS v2 API impl
-
-Kegan Dougal <kegan at matrix.org>
- * HS core
- * CS v1 API impl
- * AS API impl
-
-Paul "LeoNerd" Evans <paul at matrix.org>
- * HS core
- * Presence
- * Typing Notifications
- * Performance metrics and caching layer
-
-Dave Baker <dave at matrix.org>
- * Push notifications
- * Auth CS v2 impl
-
-Matthew Hodgson <matthew at matrix.org>
- * General doc & housekeeping
- * Vertobot/vertobridge matrix<->verto PoC
-
-Emmanuel Rohee <manu at matrix.org>
- * Supporting iOS clients (testability and fallback registration)
+----
 
 Turned to Dust <dwinslow86 at gmail.com>
  * ArchLinux installation instructions
@@ -62,16 +36,13 @@ Christoph Witzany <christoph at web.crofting.com>
  * Add LDAP support for authentication
 
 Pierre Jaury <pierre at jaury.eu>
-* Docker packaging
+ * Docker packaging
 
 Serban Constantin <serban.constantin at gmail dot com>
  * Small bug fix
 
-Jason Robinson <jasonr at matrix.org>
- * Minor fixes
-
 Joseph Weston <joseph at weston.cloud>
- + Add admin API for querying HS version
+ * Add admin API for querying HS version
 
 Benjamin Saunders <ben.e.saunders at gmail dot com>
  * Documentation improvements

CONTRIBUTING.rst

@@ -114,17 +114,6 @@ directory, you will need both a regular newsfragment *and* an entry in the
 debian changelog. (Though typically such changes should be submitted as two
 separate pull requests.)
 
-Attribution
-~~~~~~~~~~~
-
-Everyone who contributes anything to Matrix is welcome to be listed in the
-AUTHORS.rst file for the project in question. Please feel free to include a
-change to AUTHORS.rst in your pull request to list yourself and a short
-description of the area(s) you've worked on. Also, we sometimes have swag to
-give away to contributors - if you feel that Matrix-branded apparel is missing
-from your life, please mail us your shipping address to matrix at matrix.org and
-we'll try to fix it :)
-
 Sign off
 ~~~~~~~~