Updated docs for new event system
Updated docs for new event system

jirenz/CS229_Project,anuragpapineni/Hearthbreaker-evolved-agent,anuragpapineni/Hearthbreaker-evolved-agent,Ragowit/hearthbreaker,danielyule/hearthbreaker,pieiscool/edited-hearthbreaker,anuragpapineni/Hearthbreaker-evolved-agent,slaymaker1907/hearthbreaker,pieiscool/edited-hearthbreaker,slaymaker1907/hearthbreaker,kingoflolz/hearthbreaker,noa/hearthbreaker