📝 Refactor docs, "Tutorial - User Guide" and "Advanced User Guide" (#887)

docs/tutorial/query-params-str-validations.md

@@ -50,7 +50,7 @@ And then, we can pass more parameters to `Query`. In this case, the `max_length`
 q: str = Query(None, max_length=50)
 ```
 
-This will validate the data, show a clear error when the data is not valid, and document the parameter in the OpenAPI schema path operation.
+This will validate the data, show a clear error when the data is not valid, and document the parameter in the OpenAPI schema *path operation*.
 
 ## Add more validations