suppress doc warnings

doc/source/user_guide/missing_data.rst

@@ -659,6 +659,7 @@ Pass nested dictionaries of regular expressions that use the ``regex`` keyword.
 Pass a list of regular expressions that will replace matches with a scalar.
 
 .. ipython:: python
+   :okwarning:
 
    df.replace([r"\s*\.\s*", r"a|b"], np.nan, regex=True)
 
@@ -668,6 +669,7 @@ argument must be passed explicitly by name or ``regex`` must be a nested
 dictionary.
 
 .. ipython:: python
+   :okwarning:
 
    df.replace(regex=[r"\s*\.\s*", r"a|b"], value=np.nan)