DOC: Validation script checks for tabs

Add a check to validate the docstrings dont have tabs.
The documentation uses whitespace only, adding the check will prevent
tabs being added in the sprint or future submissions

Author: mariocj89

scripts/validate_docstrings.py

@@ -455,6 +455,10 @@ def validate_one(func_name):
             if not rel_desc:
                 errs.append('Missing description for '
                             'See Also "{}" reference'.format(rel_name))
+
+    if "\t" in doc.raw_doc:
+        errs.append('Tabs found in the docstring, please use whitespace only')
+
     examples_errs = ''
     if not doc.examples:
         errs.append('No examples section found')