fixed a doc string format

Author: smartvinnetou

pandas/core/generic.py

@@ -10540,7 +10540,7 @@ def _doc_parms(cls):
 
 Parameters
 ----------
-axis : {%(}axis_descr}
+axis : {axis_descr}
     Axis for the function to be applied on.
 skipna : bool, default None
     Exclude NA/null values when computing the result.