Move focus for chat to Matrix, following Haskell Foundation

Author: mpilgrem

CONTRIBUTING.md

@@ -87,11 +87,18 @@ topics, and that is reflected in the current issue tracker content. Assistance
 in responding to such matters is greatly appreciated.
 
 While support-related matters can be posted here as an 'issue', we encourage the
-use of other forums, in particular
-[Haskell's Discourse](https://discourse.haskell.org/). We also recommend
-Haskell's Discourse for general discussions about Stack's current or desired
-features. Stack is also discussed on Reddit's
-[Haskell community](https://www.reddit.com/r/haskell/).
+use of other forums, in particular the
+[Haskell Community](https://discourse.haskell.org/) forum. See its 'Learn'
+category. We also recommend that forum for general discussions about Stack's
+current or desired features.
+
+Stack is also discussed:
+
+* in the Haskell
+  [Stack and Stackage](https://matrix.to/#/#haskell-stack:matrix.org) room
+  (address `#haskell-stack:matrix.org`) on [Matrix](https://matrix.org/); and
+
+* on Reddit's [Haskell community](https://www.reddit.com/r/haskell/).
 
 We encourage use of those other forums because support-related discussions can
 clog up the issue tracker and make it more difficult to maintain the project.

README.md

@@ -20,11 +20,7 @@ If are learning to use Stack and have questions, a discussion at the
 You can participate with the Stack community in the following areas:
 
 * the [Haskell Community](https://discourse.haskell.org/) forum
-* the Haskell Foundation's
-  [Slack workspace](https://haskell-foundation.slack.com/join/shared_invite/zt-z45o9x38-8L55P27r12YO0YeEufcO2w#/shared-invite/email)
-    * `#stack-users` channel, for general Stack discussion
-    * `#stack-collaborators` channel, for working on Stack's code base
-* the [Haskell Stack room](https://matrix.to/#/#haskell-stack:matrix.org) on
-  [Matrix](https://matrix.org/)
-* the [Google Group mailing list](https://groups.google.com/g/haskell-stack) for
-  Stack
+
+* the Haskell
+  [Stack and Stackage](https://matrix.to/#/#haskell-stack:matrix.org)
+  room (address `#haskell-stack:matrix.org`) on [Matrix](https://matrix.org/)

doc/README.md

@@ -417,7 +417,7 @@ For answers to frequently asked questions about Stack, please see the
 [FAQ](faq.md).
 
 For general questions please post to the
-[Haskell Community](https://discourse.haskell.org/about).
+[Haskell Community](https://discourse.haskell.org/about) forum.
 
 ## Get involved!
 

doc/community/index.md

@@ -8,7 +8,7 @@ title: Get involved
 ## Feedback and discussion
 
 * For general comments, feedback and support, please post to the
-  [Haskell Community](https://discourse.haskell.org/about).
+  [Haskell Community](https://discourse.haskell.org/about) forum.
 * For bugs, issues, or requests, please
   [open an issue](https://github.com/commercialhaskell/stack/issues/new).
 * When using Stack Overflow, please use the

doc/maintainers/releases.md

@@ -372,38 +372,17 @@ final release.
 
     ### G: Announce the release candidate
 
-    Announce the release candidate to the following mailing lists
-
-    * [email protected]
-
-        !!! note
-
-            You have to be a member of the mailing list to post to it. See the
-            list's
-            [interface](https://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe)
-
-    * [email protected]
-
-        !!! note
-
-            Members of the group can post but posts from new members are held
-            for moderation.
-
-    * [email protected]
-
-        !!! note
-
-            Members of the group can post but posts from new members are held
-            for moderation.
-
     Announce the release candidate on the
-    [Haskell Community](https://discourse.haskell.org/c/announcements/10/l/latest).
+    [Haskell Community](https://discourse.haskell.org/c/announcements/10/l/latest)
+    forum.
 
-    Announce the release candidate in the `#stack-users` channel of the Haskell
-    Foundation's Slack workspace.
+    Announce the release candidate in the Haskell Foundation's
+    [general](https://matrix.to/#/#haskell-foundation-general:matrix.org) room
+    (address `#haskell-foundation-general:matrix.org`) on
+    [Matrix](https://matrix.org/).
 
-    Announce the release candidate in the
-    [Haskell Stack room](https://matrix.to/#/#haskell-stack:matrix.org)
+    Announce the release candidate in the Haskell
+    [Stack and Stackage](https://matrix.to/#/#haskell-stack:matrix.org) room
     (address `#haskell-stack:matrix.org`) on [Matrix](https://matrix.org/).
 
     Announce the release candidate in Reddit's
@@ -657,38 +636,17 @@ final release.
 
     ### K: Announce the release
 
-    Announce the release to the following mailing lists
-
-    * [email protected]
-
-        !!! note
-
-            You have to be a member of the mailing list to post to it. See the
-            list's
-            [interface](https://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe)
-
-    * [email protected]
-
-        !!! note
-
-            Members of the group can post but posts from new members are held
-            for moderation.
-
-    * [email protected]
-
-        !!! note
-
-            Members of the group can post but posts from new members are held
-            for moderation.
-
     Announce the release on the
-    [Haskell Community](https://discourse.haskell.org/c/announcements/10/l/latest).
+    [Haskell Community](https://discourse.haskell.org/c/announcements/10/l/latest)
+    forum.
 
-    Announce the release in the `#stack-users` channel of the Haskell
-    Foundation's Slack workspace.
+    Announce the release candidate in the Haskell Foundation's
+    [general](https://matrix.to/#/#haskell-foundation-general:matrix.org)
+    room (address `#haskell-foundation-general:matrix.org`) on
+    [Matrix](https://matrix.org/).
 
-    Announce the release in the
-    [Haskell Stack room](https://matrix.to/#/#haskell-stack:matrix.org)
+    Announce the release in the Haskell
+    [Stack and Stackage](https://matrix.to/#/#haskell-stack:matrix.org) room
     (address `#haskell-stack:matrix.org`) on [Matrix](https://matrix.org/).
 
     Announce the release in Reddit's