DOC: Update docstrings to reflect benefit from resolving #4131

1bd8f57 resolves #4131 without
updating docstrings in relevant functions.  No way to know that keep_default_na
and verbose are valid keyword arguments without inspecting the parsers.py code
and documentation

Author: davidshinn

pandas/io/excel.py

@@ -37,6 +37,11 @@ def read_excel(path_or_buf, sheetname, kind=None, **kwds):
           column ranges (e.g. "A:E" or "A,C,E:F")
     na_values : list-like, default None
         List of additional strings to recognize as NA/NaN
+    keep_default_na : bool, default True
+        If na_values are specified and keep_default_na is False the default NaN
+        values are overridden, otherwise they're appended to
+    verbose : boolean, default False
+        Indicate number of NA values placed in non-numeric columns
 
     Returns
     -------
@@ -101,6 +106,11 @@ def parse(self, sheetname, header=0, skiprows=None, skip_footer=0,
               column ranges (e.g. "A:E" or "A,C,E:F")
         na_values : list-like, default None
             List of additional strings to recognize as NA/NaN
+        keep_default_na : bool, default True
+            If na_values are specified and keep_default_na is False the default NaN
+            values are overridden, otherwise they're appended to
+        verbose : boolean, default False
+            Indicate number of NA values placed in non-numeric columns
 
         Returns
         -------