[PATCH xrandr] Document --brightness option in --help message

[Mikhail Gusarov]

This option is introduced more than two years ago, mentioned in manpage, but not
in the --help message.
---
 xrandr.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/xrandr.c b/xrandr.c
index 35dff3e..a4a9d17 100644
--- a/xrandr.c
+++ b/xrandr.c
@@ -133,6 +133,7 @@ usage(void)
     fprintf(stderr, "      --crtc <crtc>\n");
     fprintf(stderr, "      --panning <w>x<h>[+<x>+<y>[/<track:w>x<h>+<x>+<y>[/<border:l>/<t>/<r>/<b>]]]\n");
     fprintf(stderr, "      --gamma <r>:<g>:<b>\n");
+    fprintf(stderr, "      --brightness <b>\n");
     fprintf(stderr, "      --primary\n");
     fprintf(stderr, "  --noprimary\n");
     fprintf(stderr, "  --newmode <name> <clock MHz>\n");
-- 
1.7.9