Continuous Integration: display only the master branch in the README
Continuous Integration: display only the master branch in the README

This will avoid having an error displayed if the last branch build has an error while master is fine
FStarLang/FStar,A-Manning/FStar,YaccConstructor/FStar,FStarLang/FStar,FStarLang/FStar,MallabaevAzamat/FStar,A-Manning/FStar,A-Manning/FStar,MallabaevAzamat/FStar,hoheinzollern/FStar,MallabaevAzamat/FStar,hoheinzollern/FStar,YaccConstructor/FStar,YaccConstructor/FStar,YaccConstructor/FStar,MallabaevAzamat/FStar,hoheinzollern/FStar,hoheinzollern/FStar