Nobody thought to add it probably. Did a quick search on github, looks like it can be added here if someone is interested and wants to make a contribution:

• file
• lemmy-ui example
• lemmyBB example

Looks like that page could do with an update for a few apps. But it also looks like apps are spreading by word of mouth here a lot anyway.

I’d love to see someone add it! Might want to wait a few days (or at least keep the PR on hold) until a new icon is adopted though!

Shouldn’t you ask that question on https://lemmy.ml/c/lemmy_support?