sindex.1: Use ' for a plain quote char

lintian (a linter for Debian packages) warns:

N:    This manual page uses the \' groff sequence. Usually, the intent to
N:    generate an apostrophe, but that sequence actually renders as a an acute
N:    accent.
N:
N:    For an apostrophe or a single closing quote, use plain '. For single
N:    opening quote, i.e. a straight downward line ' like the one used in
N:    shell commands, use \(aq.

I'm not following its advice but stick to ' as is done in other places
of sindex.1.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Acked-by: Alexey Gladkov <gladkov.alexey@gmail.com>
1 file changed