vcgencmd: Clarify man page

A description of the get_throttled output in the vcgencmd man page
fails to include bit 0, which can be confusing. Add it.

Fixes: #53
Signed-off-by: Phil Elwell <phil@raspberrypi.com>

Author: pelwell

vcgencmd/vcgencmd.1

@@ -101,9 +101,9 @@ example:
 Adding the bit numbers along the top we get:
 .TS
 tab( );
-n n n n n n n n n n n n n n n n n n n .
-19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
-0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
+n n n n n n n n n n n n n n n n n n n n .
+19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
+0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
 .TE
 .IP
 From this we can see that bits 18 and 16 are set, indicating that the Pi has