Allow override or customization of the GitHub PR Pull Request Comments

**Is your feature request related to a problem? Please describe.**

It's frustrating when you have multiple deploys per PR (for example storybook and a React app) to remember which environment is which. "Chocolate Rain" and "Funky Monkey" don't exactly imply one or the other :)

**Describe the solution you'd like**

I would like to be able to provide a custom string in the comment that is posted to the PR. As simple as a custom comment section would be great.
As complicated as a full-blown template string would be great, but not required.

**Describe alternatives you've considered**

I've considered writing my own script to push comments to the PR or attempting to modify them after the fact. Both of them require more customization and maintenance, and the reason we use SWAs is because of how easy they are to use.

**Additional context**
N/A