Restore comment in stubgen

As pointed out by @pranavrajpal in #11498 (comment)

Author: hauntsaninja

mypy/stubgen.py

@@ -1077,7 +1077,7 @@ def visit_import_from(self, o: ImportFrom) -> None:
             self.record_name(alias or name)
 
         if self._all_:
-            # Include import forms that import names defined in __all__.
+            # Include "import from"s that import names defined in __all__.
             names = [name for name, alias in o.names
                      if name in self._all_ and alias is None and name not in IGNORED_DUNDERS]
             exported_names.update(names)