Add Audon

Although the repository was archived last month, I believe it can serve
as an educational project for others.

Signed-off-by: André Jaenisch <andre.jaenisch@posteo.de>

README.md

@@ -307,6 +307,8 @@ Emoji's for each entry provide additional information on project status:
 
 * :ghost: [**Soundstorm**](https://github.com/weathermen/soundstorm): The Federated Social Audio Platform. (Currently inactive, see [issue](https://github.com/weathermen/soundstorm/issues/21#issuecomment-882626364)) `GPL-3.0, Python`
 
+* :ghost: [**Audon**](https://codeberg.org/namekuji/audon): Audio chat space for Mastodon, Akkoma, GoToSocial, and Firefish, `AGPL-3.0-or-later, Go`
+ 
 #### Events and Meetups
 
 * [**Gancio**](https://framagit.org/les/gancio) ([site](https://gancio.org)): Shared agenda for local communities; demo [site](https://demo.gancio.org) `AGPL-3.0, JavaScript`