Dataflow GA: update GitHub's README.md to remove Beta language
Dataflow GA: update GitHub's README.md to remove Beta language

----Release Notes----
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=100331508

charlesccychen/beam,xsm110/Apache-Beam,apache/beam,manuzhang/incubator-beam,lukecwik/incubator-beam,lukecwik/incubator-beam,chamikaramj/beam,tgroh/beam,RyanSkraba/beam,amitsela/beam,joshualitt/incubator-beam,jasonkuster/incubator-beam,markflyhigh/incubator-beam,markflyhigh/incubator-beam,rangadi/beam,lukecwik/incubator-beam,chamikaramj/incubator-beam,robertwb/incubator-beam,tweise/incubator-beam,wangyum/beam,jbonofre/beam,dhalperi/incubator-beam,amitsela/incubator-beam,rangadi/incubator-beam,apache/beam,chamikaramj/beam,tgroh/incubator-beam,wangyum/beam,rangadi/beam,jasonkuster/beam,amarouni/incubator-beam,wangyum/beam,lukecwik/incubator-beam,amitsela/incubator-beam,chamikaramj/beam,apache/beam,peihe/incubator-beam,jbonofre/beam,wtanaka/beam,tweise/incubator-beam,dhananjaypatkar/DataflowJavaSDK,charlesccychen/beam,josauder/AOP_incubator_beam,markflyhigh/incubator-beam,chamikaramj/beam,RyanSkraba/beam,joshualitt/incubator-beam,staslev/incubator-beam,lukecwik/incubator-beam,apache/beam,elibixby/DataflowJavaSDK,rangadi/beam,amarouni/incubator-beam,sureshjosh/DataflowJavaSDK,Test-Betta-Inc/musical-umbrella,amitsela/beam,manuzhang/incubator-beam,manuzhang/beam,eljefe6a/incubator-beam,rangadi/beam,tgroh/incubator-beam,charlesccychen/beam,josauder/AOP_incubator_beam,staslev/incubator-beam,chamikaramj/beam,tgroh/beam,robertwb/incubator-beam,RyanSkraba/beam,markflyhigh/incubator-beam,jasonkuster/incubator-beam,robertwb/incubator-beam,robertwb/incubator-beam,lukecwik/incubator-beam,peihe/DataflowJavaSDK,dhalperi/incubator-beam,dhalperi/beam,ravwojdyla/incubator-beam,dhalperi/beam,lukecwik/incubator-beam,sammcveety/incubator-beam,lukecwik/incubator-beam,RyanSkraba/beam,iemejia/incubator-beam,peihe/DataflowJavaSDK,jbonofre/incubator-beam,apache/beam,dhananjaypatkar/DataflowJavaSDK,robertwb/incubator-beam,charlesccychen/beam,chamikaramj/beam,vikkyrk/incubator-beam,apache/beam,robertwb/incubator-beam,RyanSkraba/beam,peihe/incubator-beam,joshualitt/DataflowJavaSDK,jbonofre/incubator-beam,chamikaramj/beam,RyanSkraba/beam,ravwojdyla/incubator-beam,smarthi/DataflowJavaSDK,markflyhigh/incubator-beam,sammcveety/incubator-beam,xsm110/Apache-Beam,robertwb/incubator-beam,Test-Betta-Inc/musical-umbrella,staslev/beam,apache/beam,tyagihas/DataflowJavaSDK,apache/beam,iemejia/incubator-beam,markflyhigh/incubator-beam,sammcveety/DataflowJavaSDK,chamikaramj/beam,jasonkuster/beam,robertwb/incubator-beam,dhalperi/beam,chamikaramj/beam,mxm/incubator-beam,chamikaramj/beam,charlesccychen/incubator-beam,ahartley39/DataflowJavaSDK,lukecwik/incubator-beam,apache/beam,staslev/beam,manuzhang/beam,eljefe6a/incubator-beam,ahartley39/DataflowJavaSDK,smarthi/DataflowJavaSDK,lukecwik/incubator-beam,apache/beam,robertwb/incubator-beam,jbonofre/beam,wtanaka/beam,manuzhang/beam,joshualitt/DataflowJavaSDK,chamikaramj/incubator-beam,yk5/beam,wangyum/beam,robertwb/incubator-beam,jasonkuster/beam,vikkyrk/incubator-beam,tgroh/beam,charlesccychen/beam,yk5/beam,ravwojdyla/incubator-beam,rangadi/beam,rangadi/beam,tweise/beam,yk5/beam,tweise/beam,charlesccychen/incubator-beam,markflyhigh/incubator-beam,mxm/incubator-beam,RyanSkraba/beam,tgroh/beam,wtanaka/beam,peihe/incubator-beam,amitsela/beam,tyagihas/DataflowJavaSDK,charlesccychen/incubator-beam,sureshjosh/DataflowJavaSDK,rangadi/incubator-beam,sammcveety/DataflowJavaSDK,sammcveety/incubator-beam,charlesccychen/beam,vikkyrk/incubator-beam,elibixby/DataflowJavaSDK,staslev/beam,rangadi/incubator-beam,apache/beam,rangadi/beam,charlesccychen/beam,jbonofre/beam,xsm110/Apache-Beam,nevillelyh/DataflowJavaSDK,eljefe6a/incubator-beam