Merge branch 'ss/user-manual' into maint

Drop a few old "todo" items by deciding that the change one of them
suggests is not such a good idea, and doing the change the other
one suggested to do.

* ss/user-manual:
user-manual: add addition gitweb information
user-manual: add section documenting shallow clones
glossary: define the term shallow clone
user-manual: remove temporary branch entry from todo list

diff --cc Documentation/glossary-content.txt
Simple merge

diff --cc Documentation/user-manual.txt
Simple merge