Remove unnecessary variable

Remove total variable declaration, and add issue url for future TODO

src/pe_reports/metrics.py

@@ -19,11 +19,10 @@ def total(self):
         """Return total number of credentials."""
         df_cred_csg = self.query_cyberSix_creds.shape[0]
         df_cred_hibp = self.query_hibp_view.shape[0]
-        total = df_cred_csg + df_cred_hibp
-        return total
+        return df_cred_csg + df_cred_hibp
 
     # TODO the following functions correspond to functions at report_generator.py
-    # TODO and will be added in follow up PR's.
+    # TODO and will be added in follow up PR found here: https://github.com/cisagov/pe-reports/pull/99
     def password(self):
         """Return total number of credentials with passwords."""