[DOC] Update the Glob docs with more details

[mwichmann]

Covers xml file for manpage, very minor stuff in uguide, and docstring in code.

Also tweaked Ignore manpage entry, only because it was the very next description in Environment.xml and caught the eye.

Signed-off-by: Mats Wichmann [email protected]

Contributor Checklist:

• [ ] I have created a new test or updated the unit tests to cover the new/changed functionality.
• [X] I have updated CHANGES.txt (and read the README.rst)
• [X] I have updated the appropriate documentation