Fixed repo URL rugged → libgit2 in README Development instructions.
Fixed repo URL rugged → libgit2 in README Development instructions.

saraid/rugged,tpickett66/rugged,Acidburn0zzz/rugged,Acidburn0zzz/rugged,libgit2/rugged,saraid/rugged,spraints/rugged,tpickett66/rugged,libgit2/rugged,libgit2/rugged,spraints/rugged,Acidburn0zzz/rugged,tpickett66/rugged,saraid/rugged