add runtipi guidance

[cori]

📑 Description

There's a PR open on the Runtipi appstore repo to add 13ft to the apps provided there. If that gets merged, these additions to the README might be of interest (though I totally understand if you're not interested in publicizing this, and I may not have presented it in the most comprehensible way....

✅ Checks

• [ x ] My pull request adheres to the code style of this project if any
• [ x ] My code requires changes to the documentation
• [ x ] I have updated the documentation as required
• [x] All the tests have passed if any

ℹ Additional Information

I used Flux to generate the logo since runtipi requires one. If you have a different one you'd prefer me to use let me know. You're also welcome to use this one for whatever you want.

[cori]

I'm going to draft this until the related PR gets merged - that can take a little while sometimes.