Git_Help.rst: Clarify rejection of PRs
Git_Help.rst: Clarify rejection of PRs

Closes https://github.com/coala-analyzer/coala/issues/1827

Clarifies the Github contribution process by explaining that pull
requests may be rejected until they are found to be acceptable.

karansingh1559/coala,arush0311/coala,damngamerz/coala,coala-analyzer/coala,kartikeys98/coala,yashtrivedi96/coala,Shade5/coala,JohnS-01/coala,meetmangukiya/coala,Asnelchristian/coala,damngamerz/coala,refeed/coala,jayvdb/coala,incorrectusername/coala,arjunsinghy96/coala,RJ722/coala,meetmangukiya/coala,kartikeys98/coala,damngamerz/coala,coala-analyzer/coala,Asnelchristian/coala,JohnS-01/coala,aptrishu/coala,arjunsinghy96/coala,sagark123/coala,yashtrivedi96/coala,Nosferatul/coala,aptrishu/coala,arush0311/coala,stevemontana1980/coala,Nosferatul/coala,RJ722/coala,yashtrivedi96/coala,nemaniarjun/coala,stevemontana1980/coala,rimacone/testing2,CruiseDevice/coala,arush0311/coala,shreyans800755/coala,shreyans800755/coala,Nosferatul/coala,impmihai/coala,NiklasMM/coala,NiklasMM/coala,netman92/coala,CruiseDevice/coala,ayushin78/coala,SanketDG/coala,MariosPanag/coala,yashLadha/coala,coala/coala,RJ722/coala,sils1297/coala,CruiseDevice/coala,NiklasMM/coala,shreyans800755/coala,yashLadha/coala,netman92/coala,nemaniarjun/coala,incorrectusername/coala,Balaji2198/coala,rimacone/testing2,MariosPanag/coala,Asalle/coala,netman92/coala,coala-analyzer/coala,meetmangukiya/coala,sagark123/coala,stevemontana1980/coala,jayvdb/coala,sagark123/coala,Shade5/coala,Balaji2198/coala,incorrectusername/coala,ayushin78/coala,arjunsinghy96/coala,aptrishu/coala,refeed/coala,refeed/coala,Asnelchristian/coala,nemaniarjun/coala,Asalle/coala,coala/coala,SanketDG/coala,ayushin78/coala,MariosPanag/coala,Shade5/coala,karansingh1559/coala,karansingh1559/coala,impmihai/coala,sils1297/coala,sils1297/coala,JohnS-01/coala,Asalle/coala,rimacone/testing2,coala/coala,jayvdb/coala,SanketDG/coala,Balaji2198/coala,impmihai/coala,yashLadha/coala,kartikeys98/coala