docs: remove unnecessary whitespace

Change-Id: I11bad3de145d941b61e9bd4920bc3281ece91ab3
Signed-off-by: Spencer Oliver <spen@spen-soft.co.uk>
Reviewed-on: http://openocd.zylin.com/1245
Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>