doc/manual/style: Do not use 'Yoda conditions'

doc/manual/style: Do not use 'Yoda conditions'

For more details, see:
https://en.wikipedia.org/wiki/Yoda_conditions
https://sektorvanskijlen.wordpress.com/2019/05/16/conditional-inversion-very-harmful-myth/

Change-Id: If1a8a5f1d0fd345b7cc0c7b5dee6d0d47f9d7fc2
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: http://openocd.zylin.com/6132
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Tested-by: jenkins
Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>