revisions.txt: mark optional rev arguments with []

In revisions.txt, an optional rev argument was not distinguised.
Instead, a user had to continue and read the description in order to
learn that the argument was optional.

Since the [] notation for an optional argument is common-knowledge in
the Git documentation, mark optional arguments with [] so that it's more
obvious for the reader.

Helped-by: Andreas Heiduk <asheiduk@gmail.com>
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions