README: Update prerequisites.
README: Update prerequisites.

Bananeweizen/cgeo,SammysHP/cgeo,cgeo/cgeo,SammysHP/cgeo,Bananeweizen/cgeo,tobiasge/cgeo,pstorch/cgeo,mucek4/cgeo,matej116/cgeo,cgeo/cgeo,mucek4/cgeo,kumy/cgeo,tobiasge/cgeo,S-Bartfast/cgeo,superspindel/cgeo,S-Bartfast/cgeo,pstorch/cgeo,auricgoldfinger/cgeo,kumy/cgeo,superspindel/cgeo,cgeo/cgeo,matej116/cgeo,samueltardieu/cgeo,rsudev/c-geo-opensource,mucek4/cgeo,samueltardieu/cgeo,SammysHP/cgeo,pstorch/cgeo,auricgoldfinger/cgeo,tobiasge/cgeo,samueltardieu/cgeo,matej116/cgeo,S-Bartfast/cgeo,superspindel/cgeo,Bananeweizen/cgeo,rsudev/c-geo-opensource,auricgoldfinger/cgeo,kumy/cgeo,cgeo/cgeo,rsudev/c-geo-opensource