Add CHANGELOG notes for 1.0.0
Add CHANGELOG notes for 1.0.0

stevenmaguire/oauth2-client,jahanzaibbahadur/oauth2-client,adam-paterson/oauth2-client,hayageek/oauth2-client,nits41089/oauth2-client,thephpleague/oauth2-client,EricFu728/oauth2-client,Charykun/oauth2-client,maectpo/oauth2-client,phelipealves/oauth2-client