fix documentation error introduced by #1399 (#1402)

* fix documentation error introduced by #1399

* fix test introduced by error

Author: joesonw

protoc-gen-swagger/options/openapiv2.pb.go

@@ -28,7 +28,7 @@ message Swagger {
   // it is not included, the API is served directly under the host. The value 
   // MUST start with a leading slash (/). The basePath does not support path
   // templating.
-  // Note that using this registration option will cause many gRPC library features (such as grpc.SendHeader, etc) to stop working. Consider using `base_path` does not change the endpoint paths that are 
+  // Note that using `base_path` does not change the endpoint paths that are 
   // generated in the resulting Swagger file. If you wish to use `base_path`
   // with relatively generated Swagger paths, the `base_path` prefix must be 
   // manually removed from your `google.api.http` paths and your code changed to