gh-pr-merge: add page

[navarroaxel]

• The page (if new), does not already exist in the repo.
• The page is in the correct platform directory (common/, linux/, etc.)
• The page has 8 or fewer examples.
• The PR title conforms to the recommended templates.
• The page follows the content guidelines.
• The page description includes a link to documentation or a homepage (if applicable).

I had to investigate this command, so I publish the result of my investigation. 😁

[navarroaxel]

I think I will update the gh-pr-merge page when this issue is resolved: cli/cli#1023

[bl-ue]

Is this our first sub-subcommand? 😺

[marchersimon]

Technically platformio or ip are full of them.

[bl-ue]

Yeah, you're right, I meant "our first documented sub-subcommand"

[nicokosi]

😎