docs: twitter account @borgbackup, fixes #2948

docs/development.rst

@@ -340,7 +340,7 @@ Checklist:
 - announce on:
 
  - Mailing list
- - Twitter (follow @ThomasJWaldmann for these tweets)
+ - Twitter
  - IRC channel (change ``/topic``)
 
 - create a GitHub release, include:

docs/support.rst

@@ -38,6 +38,15 @@ unsubscribe and where you can find the archives of the list, see the
 `mailing list homepage
 <https://mail.python.org/mailman/listinfo/borgbackup>`_.
 
+Twitter
+-------
+
+Follow @borgbackup for announcements. You can also add @borgbackup if you
+would like to get retweeted for a borg related tweet.
+
+Please understand that Twitter is not suitable for longer / more complex
+discussions - use one of the other channels for that.
+
 Bounties and Fundraisers
 ------------------------