Update watchlist for client apps

watchlist-for-client-apps.md

@@ -11,4 +11,8 @@ Web apps
 
 * [Halcyon](https://notabug.org/halcyon-suite/halcyon) - [hosted instances](https://notabug.org/halcyon-suite/halcyon/wiki/Instances)
 
-* [Pinafore](https://github.com/nolanlawson/pinafore) - [hosted demo](https://pinafore.social/)
+* [Pinafore](https://github.com/nolanlawson/pinafore) - [hosted demo](https://pinafore.social/)
+
+Native apps
+
+* [WhaleBird](https://whalebird.org/) - desktop - supports GNU/Linux (.deb and .rpm)