DOC: Tidy docstring (#56307)

Tidy docstring

Author: smij720

pandas/core/base.py

@@ -108,7 +108,7 @@ class PandasObject(DirNamesMixin):
     @property
     def _constructor(self):
         """
-        Class constructor (for this class it's just `__class__`.
+        Class constructor (for this class it's just `__class__`).
         """
         return type(self)