Update README PR guidelines
Update README PR guidelines

Based on feedback so far
lorenzoYolo123/lorenzoYolo123,phase/Sponge,kenzierocks/Sponge,DDoS/Sponge,SpongeHistory/Sponge-History,Istar-Eldritch/Sponge,DDoS/SpongeForge,DDoS/SpongeForge,phase/Sponge,SRPlatin/Sponge,coaster3000/Sponge,caseif/Sponge,joseph00713/Sponge,kenzierocks/Sponge,DDoS/Sponge,Istar-Eldritch/Sponge,joseph00713/Sponge,kenzierocks/SpongeForge,SpongePowered/SpongeForge,SpongeHistory/Sponge-History,caseif/Sponge,SpongePowered/SpongeForge,kenzierocks/SpongeForge,SRPlatin/Sponge,coaster3000/Sponge,lorenzoYolo123/lorenzoYolo123