Add HeliBoard F-Droid link

Author: offa

README.md

@@ -384,7 +384,7 @@ A list of **Free** and **Open Source Software** ***(FOSS)*** for **Android** –
 * [**FlorisBoard**](https://github.com/florisboard/florisboard) <sup>**[[F-Droid](https://f-droid.org/app/dev.patrickgold.florisboard)]**</sup>
 * [**FutharkBoard**](https://github.com/DrMaxNix/futharkboard) <sup>**[[F-Droid](https://www.f-droid.org/app/de.drmaxnix.futharkboard)]**</sup>
 * [**Hacker's Keyboard**](https://github.com/klausw/hackerskeyboard) <sup>**[[F-Droid](https://f-droid.org/app/org.pocketworkstation.pckeyboard)]**</sup>
-* [**HeliBoard**](https://github.com/Helium314/HeliBoard)
+* [**HeliBoard**](https://github.com/Helium314/HeliBoard) <sup>**[[F-Droid](https://f-droid.org/app/helium314.keyboard)]**</sup>
 * [**Indic Keyboard**](https://gitlab.com/indicproject/indic-keyboard) <sup>**[[F-Droid](https://f-droid.org/app/org.smc.inputmethod.indic)]**</sup>
 * [**KryptEY**](https://github.com/amnesica/KryptEY) <sup>**[[F-Droid](https://f-droid.org/app/com.amnesica.kryptey)]**</sup>
 * [**nicoWnnG**](https://bitbucket-archive.softwareheritage.org/projects/da/dalb8/nicownng.html) <sup>**[[F-Droid](https://f-droid.org/app/net.gorry.android.input.nicownng)]**</sup>