message: Update creating operators link
diff: @@ -26,8 +26,8 @@ Contents
  ---
  - Related documents
  - - [Creating Operators](doc/operator-creation.md)
  - - [Writing Marble Tests](doc/writing-marble-tests.md)
  + - [Creating Operators](docs_app/content/guide/operators.md#creating-custom-operators)
  + - [Writing Marble Tests](docs_app/content/guide/testing/marble-testing.md)
  ---
  