Fix #6262 Incorporate Matrix room into documentation

CONTRIBUTING.md

@@ -714,3 +714,9 @@ If you're making deep changes and real-time communication with the Stack team
 would be helpful, we have a `#stack-collaborators` Slack channel in the
 Haskell Foundation workspace. To join the workspace, follow this
 [link](https://haskell-foundation.slack.com/join/shared_invite/zt-z45o9x38-8L55P27r12YO0YeEufcO2w#/shared-invite/email).
+
+## Matrix room
+
+There is also a
+[Haskell Stack room](https://matrix.to/#/#haskell-stack:matrix.org)
+at address `#haskell-stack:matrix.org` on [Matrix](https://matrix.org/).

README.md

@@ -24,4 +24,7 @@ You can participate with the Stack community in the following areas:
   [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 [Google Group mailing list](https://groups.google.com/g/haskell-stack) for Stack
+* 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

doc/README.md

@@ -325,17 +325,21 @@ label on the GitHub issue tracker.
 
 ## How to contribute to the maintenance or development of Stack
 
-The following assumes that you already have installed a version of Stack and the
-[Git application](https://git-scm.com/).
+A [guide](CONTRIBUTING.md) is provided to help potential contributors to the
+Stack project.
+
+If you have already installed a version of Stack and the
+[Git application](https://git-scm.com/) the followings steps should get you
+started with building Stack from source with Stack:
 
 1.  Clone the `stack` repository from GitHub with the command:
 
     ~~~text
     git clone https://github.com/commercialhaskell/stack.git
     ~~~
 
-2.  Change the current working directory to the cloned `stack` directory with the
-    command:
+2.  Change the current working directory to the cloned `stack` directory with
+    the command:
 
     ~~~text
     cd stack

doc/maintainers/releases.md

@@ -404,6 +404,10 @@ final release.
     Announce the release candidate in the `#stack-users` channel of the Haskell
     Foundation's Slack workspace.
 
+    Announce the release candidate in the
+    [Haskell Stack room](https://matrix.to/#/#haskell-stack:matrix.org)
+    (address `#haskell-stack:matrix.org`) on [Matrix](https://matrix.org/).
+
     Announce the release candidate in Reddit's
     [Haskell](https://www.reddit.com/r/haskell/) community.
 
@@ -674,6 +678,10 @@ final release.
     Announce the release in the `#stack-users` channel of the Haskell
     Foundation's Slack workspace.
 
+    Announce the release in the
+    [Haskell Stack room](https://matrix.to/#/#haskell-stack:matrix.org)
+    (address `#haskell-stack:matrix.org`) on [Matrix](https://matrix.org/).
+
     Announce the release in Reddit's
     [Haskell](https://www.reddit.com/r/haskell/) community.
 

doc/maintainers/team_process.md

@@ -15,7 +15,6 @@ distributed team
 ](https://github.com/commercialhaskell/stackage/blob/master/CURATORS.md))
 and we hope to replicate that success here.
 
-
 ## Goals
 
 The goals of the `Stack` maintainer team are to:
@@ -39,7 +38,6 @@ The goals of the `Stack` maintainer team are to:
 The sections below detail various activities by the `Stack` team to realize
 these goals.
 
-
 ## Issue triage
 
 The maintainer team provides ongoing review and responses to newly-filed GitHub
@@ -65,7 +63,6 @@ This is one path to getting a lot of experience with the codebase, plus great
 interaction with the rest of the maintainer team, without necessarily taking on
 major coding tasks.
 
-
 ## Time commitment
 
 Someone considering joining the issue triager team may be wondering:
@@ -86,7 +83,6 @@ process, but for now we anticipate growing the team to about eight members
 (which is the size of the `Stackage` team as well), each of whom is likely to
 spend about two hours in total on upkeep work every eight weeks.
 
-
 ## Issue and pull request interaction guidelines
 
 These guidelines apply to all members of the maintainer team.
@@ -103,7 +99,6 @@ These guidelines apply to all members of the maintainer team.
 - If you know you’ll be unable to answer for a significant period of time, say
   so. Even better: ask someone else to take over from you.
 
-
 ## Assessing feature requests and enhancement PRs
 
 **NB: this section is very likely to evolve over time as well.**
@@ -158,14 +153,12 @@ With respect to assessing a PR's code, @snoyberg has outlined some
 into his projects which may be helpful to `Stack` triagers when performing
 reviews, as well.
 
-
 ## Real-time communications
 
 At present, the maintainer team mostly communicates via a rather quiet channel
-called [`#stack-collaborators`](../CONTRIBUTING/#slack-channel) on FP
-Complete's Slack workspace, although we may migrate to some other platform in
-the near future.
-
+called [`#stack-collaborators`](../CONTRIBUTING/#slack-channel) in the
+Haskell Foundation's Slack workspace, although we may migrate to some other
+platform in the future.
 
 ## Dealing with support issues
 
@@ -177,7 +170,6 @@ maintainers team makes no guarantees about regularly checking them.
 *We may decide to offload support questions elsewhere in the future, but for
 now the most important thing is to direct users to a single destination.*
 
-
 ## Issue vs pull request
 
 Sometimes it is ambiguous whether something should be opened as an issue to
@@ -188,7 +180,6 @@ open a PR, it will _definitely_ take less time than opening an issue and
 describing the change you'd like to make. This logic can sometimes apply to
 minor code changes. Use your best judgement.
 
-
 ## Issue closing policy
 
 We need to strike a balance in issue handling between keeping a maintainable