Update downloads.md

Author: 3djc

downloads.md

@@ -113,7 +113,7 @@ Sound packs can be downloaded either through companion (the Download dialog will
 
 [Sound packs for OpenTX 2.0](http://voices-20.open-tx.org)  
 [Sound packs for OpenTX 2.1](http://voices-21.open-tx.org)  
-[SD card contents for OpenTX 2.2, with sound packs](http://downloads.open-tx.org/2.2/sdcard/)
+[SD card contents for OpenTX 2.2, with sound packs](https://downloads.open-tx.org/2.2/sdcard/)
 
 
 ## About OpenTX versions