Missing documentation

Missing documentation

[A Large Angry SCM]

The following is the list of files in the Documentation directory that 
have *NO* useful text in them at all.

	git-build-rev-cache.txt
	git-checkout-script.txt
	git-diff-script.txt
	git-format-patch-script.txt
	git-get-tar-commit-id.txt
	git-reset-script.txt
	git-rev-parse.txt
	git-show-rev-cache.txt
	gitk.txt

The list is the output of the following trivial script:

	cd Documentation
	grep -l 'Does something not yet documented.' *

If you are the/an author of one or more of these commands (or anyone 
else), please create some documentation for it.

If you care to, please review the rest of the documentation for out of 
date and/or incomplete text and either produce a patch or let Junio know 
so it can be added to the TODO list.