resolving addition comments

Author: kunalgosar

pandas/core/frame.py

@@ -4168,7 +4168,7 @@ def dropna(self, axis=0, how='any', thresh=None, subset=None,
 
         Parameters
         ----------
-        axis : {0 or 'index', 1 or 'columns'}
+        axis : {0 or 'index', 1 or 'columns'}, default 0
             Determine if rows or columns which contain missing values are
             removed.