SUBMITTING_PATCHES: link to commit message style docs
SUBMITTING_PATCHES: link to commit message style docs

Change-Id: I2090ebc43fc1c816b941a53dd89dbedf7bc61289
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/323696
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@google.com>
Reviewed-by: Jack Neus <637a03e54142c9dd2745baaba80dc7ff19c64b6c@google.com>

couchbasedeps/git-repo,GerritCodeReview/git-repo,couchbasedeps/git-repo,GerritCodeReview/git-repo,lewixliu/git-repo,lewixliu/git-repo