add 0.5.9 note for [ticket:1661]
add 0.5.9 note for [ticket:1661]

halfcrazy/sqlalchemy,bootandy/sqlalchemy,pdufour/sqlalchemy,EvaSDK/sqlalchemy,halfcrazy/sqlalchemy,inspirehep/sqlalchemy,graingert/sqlalchemy,wfxiang08/sqlalchemy,bootandy/sqlalchemy,bdupharm/sqlalchemy,ThiefMaster/sqlalchemy,pdufour/sqlalchemy,j5int/sqlalchemy,olemis/sqlalchemy,brianv0/sqlalchemy,WinterNis/sqlalchemy,alex/sqlalchemy,zzzeek/sqlalchemy,wujuguang/sqlalchemy,alex/sqlalchemy,davidfraser/sqlalchemy,dstufft/sqlalchemy,robin900/sqlalchemy,itkovian/sqlalchemy,monetate/sqlalchemy,alex/sqlalchemy,Cito/sqlalchemy,itkovian/sqlalchemy,Akrog/sqlalchemy,davidfraser/sqlalchemy,davidjb/sqlalchemy,dstufft/sqlalchemy,epa/sqlalchemy,ThiefMaster/sqlalchemy,276361270/sqlalchemy,Cito/sqlalchemy,Cito/sqlalchemy,j5int/sqlalchemy,hsum/sqlalchemy,sandan/sqlalchemy,Akrog/sqlalchemy,wujuguang/sqlalchemy,davidjb/sqlalchemy,bdupharm/sqlalchemy,EvaSDK/sqlalchemy,WinterNis/sqlalchemy,olemis/sqlalchemy,hsum/sqlalchemy,monetate/sqlalchemy,robin900/sqlalchemy,brianv0/sqlalchemy,epa/sqlalchemy,inspirehep/sqlalchemy,elelianghh/sqlalchemy,sandan/sqlalchemy,276361270/sqlalchemy,wfxiang08/sqlalchemy,graingert/sqlalchemy,elelianghh/sqlalchemy,sqlalchemy/sqlalchemy