docs: reference add options in exec page

docs/fundamentals/executor/executor-built-in-features.md

@@ -196,7 +196,8 @@ different purposes.
 - **`.metas` are statically defined.** "Static" means, e.g. from hard-coded value in the code, from a YAML file.
 - **`.runtime_args` are dynamically determined during runtime.** Means that you don't know the value before running
   the `Executor`, e.g. `pea_id`, `replicas`, `replica_id`. Those values are often related to the system/network
-  environment around the `Executor`, and less about the `Executor` itself.
+  environment around the `Executor`, and less about the `Executor` itself. They are usually set with the `Flow.add` 
+  method. See the list of options [here](https://docs.jina.ai/cli/#executor).
 
 The following fields are valid for `metas` and `runtime_args`: