Merge branch 'qn/clone-doc-use-long-form' into maint

The "git clone" documentation refers to command line options in its
description in the short form; they have been replaced with long
forms to make them more recognisable.

* qn/clone-doc-use-long-form:
  docs: git-clone: list short form of options first
  docs: git-clone: refer to long form of options