feat: add pantheon edition upgrade notice

src/content/docs/en/release/upgrade-to-ultramarine-40.mdx

@@ -17,7 +17,10 @@ You might need to update your system normally before the upgrade to 40 shows up
 
 ## Pantheon Edition
 
-TODO
+The Pantheon upgrade path isn't ready yet.
+While all of the required packages are in the UM and Terra repositories, the Pantheon desktop enviroment is broken for a variety of reasons.
+We are currently working with upstream and other partners to resolve this, but it's possible that Pantheon may be skipped, deprecated, or defered until mid-cycle.
+If you are interested in contributing to Ultramarine Pantheon, please join our [Discord](https://discord.gg/5fdPuxTg5Q) or [Matrix[](https://matrix.to/#/#hub:fyralabs.com) and let us know!
 
 ## Command line