Re: [PATCH 3/3] Documentation: tweak git diff help slightly

"Chris Torek via GitGitGadget" [off-list ref] writes:

 'git diff' [<options>] [<commit>] [--] [<path>...]
 'git diff' [<options>] --cached [<commit>] [--] [<path>...]
 'git diff' [<options>] <commit> <commit> [--] [<path>...]
+'git diff' [<options>] <commit>..<commit> [--] [<path>...]
+'git diff' [<options>] <commit>...<commit> [--] [<path>...]
 'git diff' [<options>] <blob> <blob>
 'git diff' [<options>] --no-index [--] <path> <path>

We actually are trying to wean users off of saying "diff A..B" which
is a nonsense notation, so I'd rather not to see it added here.
Describing "diff A...B" is a good idea, though.

While we have our attention on this part of the documentation, would
it make sense to also add description on invoking the combined diff
as well?