Update README PR guidelines
Update README PR guidelines

Based on feedback so far
boomboompower/SpongeAPI,jonk1993/SpongeAPI,frogocomics/SpongeAPI,JBYoshi/SpongeAPI,kenzierocks/SpongeAPI,jonk1993/SpongeAPI,kashike/SpongeAPI,Kiskae/SpongeAPI,caseif/SpongeAPI,Fozie/SpongeAPI,SpongePowered/SpongeAPI,Lergin/SpongeAPI,jamierocks/SpongeAPI,SpongeHistory/SpongeAPI-History,gabizou/SpongeAPI,joshgarde/SpongeAPI,frogocomics/SpongeAPI,joshgarde/SpongeAPI,SpongePowered/SpongeAPI,modwizcode/SpongeAPI,AlphaModder/SpongeAPI,Kiskae/SpongeAPI,kenzierocks/SpongeAPI,SpongePowered/SpongeAPI,boomboompower/SpongeAPI,gabizou/SpongeAPI,ryantheleach/SpongeAPI,kashike/SpongeAPI,jamierocks/SpongeAPI,caseif/SpongeAPI,SpongeHistory/SpongeAPI-History,DDoS/SpongeAPI,modwizcode/SpongeAPI,JBYoshi/SpongeAPI,DDoS/SpongeAPI,AlphaModder/SpongeAPI,Lergin/SpongeAPI,ryantheleach/SpongeAPI