Document that sync-all supports gc
Document that sync-all supports gc

gridaphobe/ghc,nathyong/microghc-ghc,snoyberg/ghc,holzensp/ghc,sgillespie/ghc,forked-upstream-packages-for-ghcjs/ghc,sdiehl/ghc,TomMD/ghc,sdiehl/ghc,GaloisInc/halvm-ghc,forked-upstream-packages-for-ghcjs/ghc,siddhanathan/ghc,gcampax/ghc,spacekitteh/smcghc,AlexanderPankiv/ghc,mfine/ghc,mcschroeder/ghc,vikraman/ghc,gcampax/ghc,urbanslug/ghc,mettekou/ghc,vikraman/ghc,oldmanmike/ghc,oldmanmike/ghc,snoyberg/ghc,christiaanb/ghc,sdiehl/ghc,TomMD/ghc,snoyberg/ghc,elieux/ghc,nushio3/ghc,vTurbine/ghc,olsner/ghc,oldmanmike/ghc,mfine/ghc,green-haskell/ghc,tjakway/ghcjvm,christiaanb/ghc,mcmaniac/ghc,lukexi/ghc,da-x/ghc,snoyberg/ghc,siddhanathan/ghc,ryantm/ghc,mfine/ghc,tjakway/ghcjvm,mfine/ghc,AlexanderPankiv/ghc,mcmaniac/ghc,nushio3/ghc,tjakway/ghcjvm,olsner/ghc,TomMD/ghc,ekmett/ghc,christiaanb/ghc,tibbe/ghc,nomeata/ghc,ghc-android/ghc,gcampax/ghc,frantisekfarka/ghc-dsi,gridaphobe/ghc,nomeata/ghc,ghc-android/ghc,nushio3/ghc,mcschroeder/ghc,wxwxwwxxx/ghc,gcampax/ghc,tjakway/ghcjvm,GaloisInc/halvm-ghc,ezyang/ghc,ezyang/ghc,tjakway/ghcjvm,frantisekfarka/ghc-dsi,wxwxwwxxx/ghc,ml9951/ghc,ghc-android/ghc,TomMD/ghc,ekmett/ghc,holzensp/ghc,sdiehl/ghc,fmthoma/ghc,olsner/ghc,bitemyapp/ghc,mettekou/ghc,da-x/ghc,christiaanb/ghc,sdiehl/ghc,anton-dessiatov/ghc,ezyang/ghc,hferreiro/replay,mcmaniac/ghc,nushio3/ghc,nathyong/microghc-ghc,frantisekfarka/ghc-dsi,vTurbine/ghc,anton-dessiatov/ghc,nushio3/ghc,gridaphobe/ghc,siddhanathan/ghc,gridaphobe/ghc,ghc-android/ghc,GaloisInc/halvm-ghc,hferreiro/replay,nkaretnikov/ghc,nathyong/microghc-ghc,forked-upstream-packages-for-ghcjs/ghc,AlexanderPankiv/ghc,bitemyapp/ghc,green-haskell/ghc,urbanslug/ghc,lukexi/ghc-7.8-arm64,anton-dessiatov/ghc,AlexanderPankiv/ghc,sgillespie/ghc,nushio3/ghc,nomeata/ghc,tibbe/ghc,fmthoma/ghc,ml9951/ghc,acowley/ghc,olsner/ghc,ml9951/ghc,nomeata/ghc,hferreiro/replay,vTurbine/ghc,mfine/ghc,da-x/ghc,urbanslug/ghc,mcschroeder/ghc,olsner/ghc,urbanslug/ghc,tibbe/ghc,shlevy/ghc,wxwxwwxxx/ghc,elieux/ghc,ilyasergey/GHC-XAppFix,shlevy/ghc,fmthoma/ghc,mettekou/ghc,nathyong/microghc-ghc,ml9951/ghc,elieux/ghc,nushio3/ghc,mcschroeder/ghc,acowley/ghc,ilyasergey/GHC-XAppFix,jstolarek/ghc,jstolarek/ghc,ghc-android/ghc,da-x/ghc,spacekitteh/smcghc,TomMD/ghc,shlevy/ghc,nomeata/ghc,forked-upstream-packages-for-ghcjs/ghc,spacekitteh/smcghc,AlexanderPankiv/ghc,gridaphobe/ghc,spacekitteh/smcghc,nkaretnikov/ghc,sgillespie/ghc,fmthoma/ghc,tjakway/ghcjvm,elieux/ghc,fmthoma/ghc,hferreiro/replay,vTurbine/ghc,anton-dessiatov/ghc,ezyang/ghc,olsner/ghc,elieux/ghc,christiaanb/ghc,lukexi/ghc-7.8-arm64,ezyang/ghc,mfine/ghc,forked-upstream-packages-for-ghcjs/ghc,ilyasergey/GHC-XAppFix,frantisekfarka/ghc-dsi,siddhanathan/ghc,holzensp/ghc,ghc-android/ghc,GaloisInc/halvm-ghc,acowley/ghc,vikraman/ghc,shlevy/ghc,ryantm/ghc,lukexi/ghc,forked-upstream-packages-for-ghcjs/ghc,GaloisInc/halvm-ghc,fmthoma/ghc,elieux/ghc,oldmanmike/ghc,christiaanb/ghc,vTurbine/ghc,mettekou/ghc,gcampax/ghc,ekmett/ghc,elieux/ghc,sgillespie/ghc,nkaretnikov/ghc,sgillespie/ghc,nathyong/microghc-ghc,wxwxwwxxx/ghc,wxwxwwxxx/ghc,GaloisInc/halvm-ghc,mcschroeder/ghc,siddhanathan/ghc,bitemyapp/ghc,shlevy/ghc,jstolarek/ghc,hferreiro/replay,ryantm/ghc,nkaretnikov/ghc,oldmanmike/ghc,acowley/ghc,nathyong/microghc-ghc,AlexanderPankiv/ghc,vTurbine/ghc,oldmanmike/ghc,lukexi/ghc-7.8-arm64,wxwxwwxxx/ghc,bitemyapp/ghc,mettekou/ghc,ghc-android/ghc,lukexi/ghc-7.8-arm64,gridaphobe/ghc,ml9951/ghc,ilyasergey/GHC-XAppFix,mfine/ghc,urbanslug/ghc,ekmett/ghc,anton-dessiatov/ghc,ezyang/ghc,christiaanb/ghc,mettekou/ghc,snoyberg/ghc,lukexi/ghc-7.8-arm64,da-x/ghc,anton-dessiatov/ghc,gridaphobe/ghc,vikraman/ghc,tibbe/ghc,jstolarek/ghc,mcmaniac/ghc,vTurbine/ghc,vikraman/ghc,urbanslug/ghc,sgillespie/ghc,lukexi/ghc,green-haskell/ghc,lukexi/ghc,nkaretnikov/ghc,holzensp/ghc,bitemyapp/ghc,sgillespie/ghc,mcmaniac/ghc,ryantm/ghc,green-haskell/ghc,olsner/ghc,fmthoma/ghc,sdiehl/ghc,acowley/ghc,holzensp/ghc,hferreiro/replay,GaloisInc/halvm-ghc,snoyberg/ghc,tibbe/ghc,ryantm/ghc,tjakway/ghcjvm,TomMD/ghc,nkaretnikov/ghc,da-x/ghc,ezyang/ghc,wxwxwwxxx/ghc,vikraman/ghc,ml9951/ghc,TomMD/ghc,mettekou/ghc,forked-upstream-packages-for-ghcjs/ghc,shlevy/ghc,jstolarek/ghc,AlexanderPankiv/ghc,siddhanathan/ghc,acowley/ghc,sdiehl/ghc,ml9951/ghc,ml9951/ghc,nkaretnikov/ghc,ekmett/ghc,vikraman/ghc,mcschroeder/ghc,spacekitteh/smcghc,gcampax/ghc,snoyberg/ghc,siddhanathan/ghc,anton-dessiatov/ghc,urbanslug/ghc,acowley/ghc,mcschroeder/ghc,frantisekfarka/ghc-dsi,da-x/ghc,oldmanmike/ghc,green-haskell/ghc,lukexi/ghc,nathyong/microghc-ghc,gcampax/ghc,shlevy/ghc,hferreiro/replay