docs: Update macOS protoc installation instructions
docs: Update macOS protoc installation instructions

kklin/quilt,quilt/quilt,kklin/quilt,kelda/kelda,kklin/quilt,ejj/quilt-dev,kklin/quilt,NetSys/quilt,NetSys/quilt,ejj/quilt-dev,kelda/kelda,LuiseV/quilt,ejj/quilt-dev,kelda/kelda,kelda/kelda,kklin/kelda,LuiseV/quilt,NetSys/quilt,LuiseV/quilt,LuiseV/quilt,quilt/quilt,kklin/kelda,LuiseV/quilt,NetSys/quilt,kklin/kelda,kklin/kelda,quilt/quilt,NetSys/quilt,ejj/quilt-dev,quilt/quilt