Documentation: Allow custom diff tools to be specified in 'diff.tool'
Documentation: Allow custom diff tools to be specified in 'diff.tool'

Apart from the list of "valid values", 'diff.tool' can take any value,
provided there is a corresponding 'difftool.<tool>.cmd' option.  Also,
describe this option just before the 'difftool.*' options.

Helped-by: Michael J Gruber <46f1a0bd5592a2f9244ca321b129902a06b53e03@drmicha.warpmail.net>
Signed-off-by: Ramkumar Ramachandra <5c355d1d38066ed0c5de420d67c1b5ed0687c4bd@gmail.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git