log doc: the argument to --encoding is not optional
$ git log --encoding
fatal: Option '--encoding' requires a value
$ git rev-list --encoding
fatal: Option '--encoding' requires a value
The argument to --encoding has always been mandatory. Unfortunately
manpages like git-rev-list(1), git-log(1), and git-show(1) have
described the option's syntax as "--encoding[=<encoding>]" since it
was first documented. Clarify by removing the extra brackets.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>