tests: update semaphore documentation
tests: update semaphore documentation

The Semaphore configuration UI changed. Update the documentation
accordingly.

yifan-gu/rkt,sstabellini/rkt,mike1729/rkt,ybubnov/rkt,Wilybald/rkt,Wilybald/rkt,tmrts/rkt,matthaias/rkt,achanda/rkt,joshix/rkt,yifan-gu/rkt,dgonyeo/rkt,krnowak/rkt,jonboulle/rkt,jjlakis/rkt,matthaias/rkt,blixtra/rkt,nhlfr/rkt,linki/rkt,akshaykarle/rkt,s-urbaniak/rkt,sgotti/rkt,kbrwn/rkt,Wilybald/rkt,lucasallan/rkt,intelsdi-x/rkt,akshaykarle/rkt,mike1729/rkt,jjlakis/rkt,liugenping/rkt,s-urbaniak/rkt,jonboulle/rkt,shobhit85/rkt,jzelinskie/rkt,akshaykarle/rkt,coreos/rkt,intelsdi-x/rkt,markllama/rkt,jzelinskie/rkt,euank/rkt,matthaias/rkt,jakon89/rkt,jonboulle/rkt,endocode/rkt,cab105/rkt,endocode/rkt,jasonchaffee/rkt,Wilybald/rkt,s-urbaniak/rkt,adfernandes/rkt,sgotti/rkt,cab105/rkt,kinvolk/rkt,Shashwatsh/rkt,tmrts/rkt,euank/rkt,mike1729/rkt,liugenping/rkt,sstabellini/rkt,sinfomicien/rkt,linki/rkt,Shashwatsh/rkt,jasonchaffee/rkt,euank/rkt,jjlakis/rkt,intelsdi-x/rkt,squeed/rkt,coreos/rkt,markllama/rkt,ybubnov/rkt,il9ue/rkt,sstabellini/rkt,monstermunchkin/rkt,lucasallan/rkt,achanda/rkt,adfernandes/rkt,shobhit85/rkt,jzelinskie/rkt,Shashwatsh/rkt,jakon89/rkt,il9ue/rkt,kbrwn/rkt,endocode/rkt,yifan-gu/rocket,yifan-gu/rocket,cab105/rkt,yifan-gu/rocket,kinvolk/rkt,joshix/rkt,markllama/rkt,dgonyeo/rkt,adfernandes/rkt,liugenping/rkt,squeed/rkt,tmrts/rkt,rkt/rkt,kinvolk/rkt,joshix/rkt,alban/rkt,alban/rkt,blixtra/rkt,alban/rkt,il9ue/rkt,monstermunchkin/rkt,sgotti/rkt,rkt/rkt,yifan-gu/rkt,kinvolk/rkt,coreos/rkt,lucasallan/rkt,rkt/rkt,dgonyeo/rkt,jakon89/rkt,shobhit85/rkt,sinfomicien/rkt,ybubnov/rkt,lucasallan/rkt,monstermunchkin/rkt,nhlfr/rkt,rkt/rkt,squeed/rkt,joshix/rkt,blixtra/rkt,sinfomicien/rkt,jasonchaffee/rkt,krnowak/rkt,nhlfr/rkt,achanda/rkt,linki/rkt,kbrwn/rkt,krnowak/rkt