First, all man pages highlight only perf and subcommands except 'perf
kallsyms', which includes the full usage. Fix it for commands to
monopolize underlines.

Second, options can be ommited when executing 'perf kallsyms', so add
square brackets between <option>.
Signed-off-by: NSangwon Hong <qpakzk@gmail.com>
Acked-by: NNamhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Taeung Song <treeze.taeung@gmail.com>
Link: http://lkml.kernel.org/r/1518377864-20353-1-git-send-email-qpakzk@gmail.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>