Made changes as recommended

Author: thoo

scripts/validate_docstrings.py

@@ -502,7 +502,7 @@ def validate_one(func_name):
             if rel_name.startswith('pandas.'):
                 errs.append('{} in `See Also` section does not '
                             'need `pandas` prefix, use {} instead.'
-                            .format(rel_name, rel_name.replace('pandas.', '')))
+                            .format(rel_name, rel_name[len('pandas.'):]))
     for line in doc.raw_doc.splitlines():
         if re.match("^ *\t", line):
             errs.append('Tabs found at the start of line "{}", '