docs: integrate COMMITSTYLE

Make a symlink at docs/merge-requests/commitstyle.md that points at the
COMMITSTYLE.md file, so it is part of the documentation at
https://docs.postmarketos.org/pmaports/.

Tweak the headline and link to Alpine's COMMITSTYLE.md so it looks
better in the version rendered at docs.postmarketos.org.

Signed-off-by: Oliver Smith <ollieparanoid@postmarketos.org>
Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/8829>

COMMITSTYLE.md

@@ -1,4 +1,4 @@
-# Policy for commits in pmaports
+# Commit Style
 
 This document defines policy for organising and titling commits for
 inclusion in pmaports.
@@ -16,9 +16,9 @@ target device.
 
 ## General policy
 
-We follow Alpine's aports commit style with some minor exceptions
-and additions. Alpine's commit style can be found here:
-https://gitlab.alpinelinux.org/alpine/aports/-/blob/master/COMMITSTYLE.md
+We follow
+[Alpine's aports commit style](https://gitlab.alpinelinux.org/alpine/aports/-/blob/master/COMMITSTYLE.md)
+with some minor exceptions and additions.
 
 ## Exceptions
 

docs/merge-requests.md

@@ -7,5 +7,6 @@ The subpages of this page describe processes for merge requests in pmaports.
    :hidden:
 
    merge-requests/approval-rules
+   merge-requests/commitstyle
    merge-requests/stable-branches
 ```

docs/merge-requests/commitstyle.md

@@ -0,0 +1 @@
+../../COMMITSTYLE.md