Python: Fix potential code generation issue of documentation comment.

src/idl_gen_python.cpp

@@ -493,7 +493,7 @@ static void GenStruct(const StructDef &struct_def,
                       StructDef *root_struct_def) {
   if (struct_def.generated) return;
 
-  GenComment(struct_def.doc_comment, code_ptr, nullptr);
+  GenComment(struct_def.doc_comment, code_ptr, nullptr, "# ");
   BeginClass(struct_def, code_ptr);
   if (&struct_def == root_struct_def) {
     // Generate a special accessor for the table that has been declared as
@@ -660,5 +660,3 @@ bool GeneratePython(const Parser &parser,
 }
 
 }  // namespace flatbuffers
-
-

tests/monster_test.fbs

@@ -31,6 +31,7 @@ table Stat {
   count:ushort;
 }
 
+/// an example documentation comment: monster object
 table Monster {
   pos:Vec3 (id: 0);
   hp:short = 100 (id: 2);