OpenTofu compatibility badge

[virtualroot]

![OpenTofu compatibility](https://img.shields.io/badge/OpenTofu-Compatible-FFDA18?logo=opentofu&logoColor=white)

From https://github.com/DevSecTop/TF-via-PR-Comments

[rdhar]

Hey, thanks for the link back to the repo!

Shout-out to Shields.io's Static Badge Generator as well as Simple Icons for enabling me to put together this badge.

And here's a hi-res PNG version of it 😄