youtube: added freetube to alternative frontends

wiki/youtube.md

@@ -6,9 +6,14 @@
 
 There are some alternative frontends available that also feature user managament
 including subscriptions.
-A self-hosting alternative is [Invidious](/wiki/invidious.md).
+
-For [Android](/wiki/android.md) phones [NewPipe](https://github.com/TeamNewPipe/NewPipe) is
+- [Invidious](/wiki/invidious.md) is self-hosted and provides a cross-platform web service.
-available in the [F-Droid Appstore](/wiki/android/f-droid.md).
+  This frontend allows the usage of [SponsorBlock](#automatically-skip-sponsorships).
+- [FreeTube](https://freetubeapp.io/) is a alternative frontend that provides a local desktop
+  application for [Linux](/wiki/linux.md), Mac and [Windows](/wiki/windows.md) systems.
+  This application has [SponsorBlock](#automatically-skip-sponsorships) built in.
+- [NewPipe](https://github.com/TeamNewPipe/NewPipe) for [Android](/wiki/android.md) phones is an
+  application that is available via the [F-Droid Appstore](/wiki/android/f-droid.md).
 
 ## Downloading YouTube Videos