Clarify HOL3 based on participant feedback

[sswart]

A participant offered the following feedback:

03-Staged-deployments.md

“Add a input of the type environment to the workflow_dispatch trigger.”

I am not so familiar with GitHub. Therefore, I searched for a place (Button, section, etc.) for the triggers. Maybe a small
remainder that the triggers are predefined can be helpful)

Also, you don’t mention in which file we should add this. I was confused because multiple files in the “workflows” directory
contains this trigger.

I added a small clarification to avoid future confusion,