exno: firmware update instructions

en/exposure_notifications.md

@@ -14,7 +14,7 @@ a Merge Request which implements this functionality. If you have a working toolc
 please try and build this MR, as you will have to most up-to-date version.
 
 If you do not have a working toolchain, you can download a [pre-build image](/release/card10-exno-r1.zip).
-Simply unzip the archive and merge it onto your card10. See the [firmware update page](firmwareupdate) for details. Most importantly
+Simply unzip the archive and merge it onto your card10. See the [firmware update page](/en/firmwareupdate) for details. Most importantly
 always use the "safely eject" functionality of your operating system after writing files to the card10.
 
 To use the BLE features of the card10 make sure to enable BLE in the `Bluetooth` app.

en/firmwareupdate.md

@@ -15,6 +15,15 @@ title: Current Release
 
 ---
 
+# Experimental Releases
+
+These releases are untested and must be considered faulty. Always create a backup of the files on your
+card10 before applying them. Please follow the steps mentioned above.
+
+- [Exposure Notifications](/en/exposure_notifications.md): https://card10.badge.events.ccc.de/release/card10-exno-r1.zip
+
+---
+
 # Previous Releases
 # Nettle (2019-12-29)
 - Firmware Download: https://card10.badge.events.ccc.de/release/card10-v1.14-Nettle.zip