Most of the exact option strings to be typed by end users are
already set in typewriter font by using `--option`, but a few places
used '--option' to call for italics or with no quoting. Uniformly
use `--option`.
Also add a full-stop after a sentence that missed one.
Signed-off-by: Vincent van Ravesteijn <vfr@lyx.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>