Adds guidelines for commit message formatting with rules
from Chris Beams' blog post here:

https://chris.beams.io/posts/git-commit/



Signed-off-by: Alex Ellis <alexellis2@gmail.com>

Note, not all `alexellis/github` references should be changed, there are
a number of repos which are not part of the openfaas org, this commit
excludes those.

Signed-off-by: John McCabe <john@johnmccabe.net>

Signed-off-by: rgee0 <richard@technologee.co.uk>

Signed-off-by: Alex Ellis <alexellis2@gmail.com>

Signed-off-by: Alex Ellis <alexellis2@gmail.com>