[docs] [issue19980] Improve help('non-topic') response

Mark Lawrence added the comment: LGTM. I noticed this running the tests. test_modules (test.test_pydoc.PydocImportTest) ... skipped 'causes undesireable side-effects (#20128)' test_modules_search (test.test_pydoc.PydocImportTest) ... skipped 'causes undesireable side-effects (#20128)' test_modules_search_builtin (test.test_pydoc.PydocImportTest) ... skipped 'some buildbots are not cooperating (#20128)' ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue19980> _______________________________________