Jeff King authored May 13, 2015 and Junio C Hamano committed May 12, 2015

Older versions of AsciiDoc would convert the "--" in
"--option" into an emdash. According to 565e135a
(Documentation: quote double-dash for AsciiDoc, 2011-06-29),
this is fixed in AsciiDoc 8.3.0. According to bf171262

, we
don't support anything older than 8.4.1 anyway, so we no
longer need to worry about quoting.

Even though this does not change the output at all, there
are a few good reasons to drop the quoting:

  1. It makes the source prettier to read.

  2. We don't quote consistently, which may be confusing when
     reading the source.

  3. Asciidoctor does not like the quoting, and renders a
     literal backslash.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>