Add info about Wire 2 when Git over SSH (#20619)

- Follow up of #20616. Add a note about this in the config cheat
sheet, given there's no dedicated page for this.

custom/conf/app.example.ini

@@ -632,6 +632,7 @@ ROUTER = console
 ;GC_ARGS =
 ;;
 ;; If use git wire protocol version 2 when git version >= 2.18, default is true, set to false when you always want git wire protocol version 1
+;; To enable this for Git over SSH when using a OpenSSH server, add `AcceptEnv GIT_PROTOCOL` to your sshd_config file.
 ;ENABLE_AUTO_GIT_WIRE_PROTOCOL = true
 ;;
 ;; Respond to pushes to a non-default branch with a URL for creating a Pull Request (if the repository has them enabled)

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -964,7 +964,8 @@ Default templates for project boards:
 - `COMMITS_RANGE_SIZE`: **50**: Set the default commits range size
 - `BRANCHES_RANGE_SIZE`: **20**: Set the default branches range size
 - `GC_ARGS`: **\<empty\>**: Arguments for command `git gc`, e.g. `--aggressive --auto`. See more on http://git-scm.com/docs/git-gc/
-- `ENABLE_AUTO_GIT_WIRE_PROTOCOL`: **true**: If use Git wire protocol version 2 when Git version >= 2.18, default is true, set to false when you always want Git wire protocol version 1
+- `ENABLE_AUTO_GIT_WIRE_PROTOCOL`: **true**: If use Git wire protocol version 2 when Git version >= 2.18, default is true, set to false when you always want Git wire protocol version 1.
+  To enable this for Git over SSH when using a OpenSSH server, add `AcceptEnv GIT_PROTOCOL` to your sshd_config file.
 - `PULL_REQUEST_PUSH_MESSAGE`: **true**: Respond to pushes to a non-default branch with a URL for creating a Pull Request (if the repository has them enabled)
 - `VERBOSE_PUSH`: **true**: Print status information about pushes as they are being processed.
 - `VERBOSE_PUSH_DELAY`: **5s**: Only print verbose information if push takes longer than this delay.