Update README.md for Discourse Info (#900)
Update README.md for Discourse Info (#900)

I replaced the info for the old Community with the info for the new Discourse one and added a link to the Community under Resources.
igniterealtime/Openfire,guusdk/Openfire,akrherz/Openfire,speedy01/Openfire,igniterealtime/Openfire,akrherz/Openfire,Gugli/Openfire,Gugli/Openfire,GregDThomas/Openfire,GregDThomas/Openfire,speedy01/Openfire,Gugli/Openfire,igniterealtime/Openfire,GregDThomas/Openfire,guusdk/Openfire,speedy01/Openfire,guusdk/Openfire,guusdk/Openfire,guusdk/Openfire,akrherz/Openfire,GregDThomas/Openfire,Gugli/Openfire,speedy01/Openfire,akrherz/Openfire,Gugli/Openfire,igniterealtime/Openfire,igniterealtime/Openfire,speedy01/Openfire,GregDThomas/Openfire,akrherz/Openfire