Documentation: fix graph in git-rev-parse.txt
Documentation: fix graph in git-rev-parse.txt

Preformatted html and man pages show a mangled graph, caused by a
backslash.

Commit f1ec6b22a8c1ab1cca0f1875f85aea5d2434e5a6 fixed this same issue,
but it seems that new versions of the Asciidoc toolchain changed their
behaviour.

Signed-off-by: Michele Ballabio <6d29a3bf69c43ceb7b71ca8c4643bffed2f4d310@katamail.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