User Manual: Write "Git" instead of "GIT"

In the Table of Contents, there is a notable inconsistency: first there is "GIT Glossary", followed by "Git Quick Reference" on the very next line. Running "grep -c" on user-manual.txt, I find 780 occurrrences of "git", 37 occurrences of "Git", and 9 occurrences of "GIT". In general, "git" is the preferred spelling, except at the beginning of a sentence. Therefore, change "GIT Glossary" to "Git Glossary" for consistency with the rest of the document. Looking at the other eight occurrences of "GIT" I found one other occurrence that should be changed: * The mention of "StGIT". Looking at the web pages for "Stacked Git" at http://www.procode.org/stgit, I only saw the spelling "StGit", except in http://wiki.procode.org/cgi-bin/wiki.cgi/StGIT_Tutorial, but that page was last updated in 2006. The other seven occurrences should not be changed: * Three occurrences were in the output of 'git show-branch' run on the git.git repository. * One occurrence was in the output of 'git cat-file'. * One occurrence was as part of the file name "GIT-VERSION-GEN". * Two occurrences were in comments in scripts quoted in a description of Tony Luck's workflow. Signed-off-by: Björn Gustavsson <bgustavsson@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>