CODING_CONVENTIONS: Add reference to IS_ACTIVE and IS_USED macros.
CODING_CONVENTIONS: Add reference to IS_ACTIVE and IS_USED macros.

x3ro/RIOT,jasonatran/RIOT,yogo1212/RIOT,basilfx/RIOT,aeneby/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,yogo1212/RIOT,x3ro/RIOT,mtausig/RIOT,kYc0o/RIOT,josephnoir/RIOT,toonst/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,ant9000/RIOT,miri64/RIOT,toonst/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,aeneby/RIOT,ant9000/RIOT,basilfx/RIOT,ant9000/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,smlng/RIOT,toonst/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,x3ro/RIOT,authmillenon/RIOT,aeneby/RIOT,OTAkeys/RIOT,aeneby/RIOT,miri64/RIOT,basilfx/RIOT,smlng/RIOT,ant9000/RIOT,authmillenon/RIOT,OTAkeys/RIOT,x3ro/RIOT,authmillenon/RIOT,kaspar030/RIOT,josephnoir/RIOT,smlng/RIOT,x3ro/RIOT,kaspar030/RIOT,ant9000/RIOT,mtausig/RIOT,smlng/RIOT,jasonatran/RIOT,authmillenon/RIOT,OTAkeys/RIOT,kYc0o/RIOT,kYc0o/RIOT,aeneby/RIOT,miri64/RIOT,toonst/RIOT,miri64/RIOT,kYc0o/RIOT,yogo1212/RIOT,mtausig/RIOT,toonst/RIOT,authmillenon/RIOT,kYc0o/RIOT,josephnoir/RIOT,OTAkeys/RIOT,smlng/RIOT,josephnoir/RIOT,yogo1212/RIOT,josephnoir/RIOT,basilfx/RIOT,authmillenon/RIOT,jasonatran/RIOT,kaspar030/RIOT,jasonatran/RIOT,mtausig/RIOT,basilfx/RIOT,miri64/RIOT,yogo1212/RIOT,mtausig/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT