Add play-pac4j in Modules.md
Add play-pac4j in Modules.md

zaneli/playframework,hagl/playframework,mkurz/playframework,mkurz/playframework,aradchykov/playframework,ktoso/playframework,benmccann/playframework,rajeshpg/playframework,playframework/playframework,marcospereira/playframework,wsargent/playframework,wsargent/playframework,rajeshpg/playframework,richdougherty/playframework,Shruti9520/playframework,aradchykov/playframework,benmccann/playframework,hagl/playframework,aradchykov/playframework,marcospereira/playframework,marcospereira/playframework,wegtam/playframework,rajeshpg/playframework,marcospereira/playframework,ktoso/playframework,wegtam/playframework,Shruti9520/playframework,Shruti9520/playframework,zaneli/playframework,Shenker93/playframework,richdougherty/playframework,wsargent/playframework,aradchykov/playframework,hagl/playframework,ktoso/playframework,Shenker93/playframework,Shenker93/playframework,zaneli/playframework,wegtam/playframework,richdougherty/playframework,playframework/playframework,rajeshpg/playframework,mkurz/playframework,playframework/playframework,benmccann/playframework,Shruti9520/playframework,wegtam/playframework,wsargent/playframework,benmccann/playframework,mkurz/playframework,hagl/playframework,Shenker93/playframework,zaneli/playframework,ktoso/playframework,richdougherty/playframework