Fix Sphinx warning caused by too short underline.
Fix Sphinx warning caused by too short underline.

marko-asplund/slick,xavier-fernandez/slick,nremond/slick,Radsaggi/slick,AtkinsChang/slick,Asamsig/slick,trevorsibanda/slick,kwark/slick,nremond/slick,xavier-fernandez/slick,knoldus/slick-1,AtkinsChang/slick,nafg/slick,knoldus/slick-1,nremond/slick,xavier-fernandez/slick,Radsaggi/slick