Missing how to create a patch in the How to Contribute document.

According to this document,
https://cwiki.apache.org/confluence/display/AMBARI/How+to+Commit

Committers will apply patches with "patch" command. (why not "git apply"?)
In order to make a patch compatible with "patch", contributors will have to

git checkout your_fix_branch
git diff trunk... --no-prefix > AMBARI-0000.patch

but it is not clear in How to Contribute document
https://cwiki.apache.org/confluence/display/AMBARI/How+to+Contribute

Two solutions;
1. Add the piece of git commands above in the How to Contribute document.
2. Or, commiters use "git apply" which is compatible with "git diff trunk..."

I'd prefer 2 since it is more git's good practice, but will let the community decide which one is preferred.