how to add a custom action to slash plugin which adds arbitrary markdown to the editor state?

[G3root]

is there any way to insert arbitrary markdown like below by an action

# Project Title
## Run Locally
### Run Locally

[Saul-Mirone]

There's no direct API to do this, but it won't hard, you can do something like this:
https://codesandbox.io/s/milkdown-listener-count-eteqe?file=/src/index.ts:1427-1572