doc: add labels documentation.
doc: add labels documentation.

mildis/traefik,FriggaHel/traefik,aantono/traefik,timoreimann/traefik,SantoDE/traefik,marco-jantke/traefik,mildis/traefik,marco-jantke/traefik,nmengin/traefik,containous/traefik,seryl/traefik,EmileVauge/traefik,mihaitodor/traefik,tanyadegurechaff/traefik,ldez/traefik,tanyadegurechaff/traefik,timoreimann/traefik,mildis/traefik,timoreimann/traefik,aantono/traefik,dtomcej/traefik,dtomcej/traefik,kekoav/traefik,jangie/traefik,mihaitodor/traefik,bparli/traefik,EmileVauge/traefik,tanyadegurechaff/traefik,thomasbach76/traefik,adityacs/traefik,containous/traefik,vdemeester/traefik,thomasbach76/traefik,adityacs/traefik,thomasbach76/traefik,ldez/traefik,FriggaHel/traefik,mvdstam/traefik,dtomcej/traefik,SantoDE/traefik,vholovko/traefik,martinbaillie/traefik,vholovko/traefik,SantoDE/traefik,thomasbach76/traefik,mvdstam/traefik,aantono/traefik,kekoav/traefik,seryl/traefik,EmileVauge/traefik,simbas/traefik,kekoav/traefik,martinbaillie/traefik,adityacs/traefik,simbas/traefik,simbas/traefik,containous/traefik,mihaitodor/traefik,seryl/traefik,aantono/traefik,vdemeester/traefik,mmatur/traefik,jangie/traefik,mihaitodor/traefik,nmengin/traefik,FriggaHel/traefik,vholovko/traefik,nmengin/traefik,mvdstam/traefik,FriggaHel/traefik,aantono/traefik,bparli/traefik,vdemeester/traefik,martinbaillie/traefik,vholovko/traefik,simbas/traefik,jangie/traefik,jangie/traefik,seryl/traefik,containous/traefik,SantoDE/traefik,vdemeester/traefik,ldez/traefik,adityacs/traefik,nmengin/traefik,martinbaillie/traefik,marco-jantke/traefik,mvdstam/traefik,ldez/traefik,tanyadegurechaff/traefik,mildis/traefik,timoreimann/traefik,bparli/traefik,mmatur/traefik,dtomcej/traefik,mmatur/traefik,mmatur/traefik,kekoav/traefik,bparli/traefik,marco-jantke/traefik,EmileVauge/traefik