info about updating to RC

Author: Daniel Hansson

README.md

@@ -49,6 +49,24 @@ https://github.com/techandme/NextBerry or here https://www.techandme.se/nextberr
 
 We call it NextBerry and it's confirmed to be working on Raspberry Pi 2 & 3.
 
+## I want to test RC!
+No problem! We made it simple. Run `update.sh` but abort it before it starts so that you have the latest `nextcloud_update.sh`. Then put this in your `nextcloud_update.sh` below the curl command (lib.sh) but before everything else and run it:
+
+To test a specific RC version:
+
+```
+NCREPO="https://download.nextcloud.com/server/prereleases"
+NCVERSION=12.0.1RC5
+STABLEVERSION="nextcloud-$NCVERSION"
+```
+
+Or the latest RC:
+```
+NCREPO="https://download.nextcloud.com/server/prereleases"
+NCVERSION=$(curl -s -m 900 $NCREPO/ | sed --silent 's/.*href="nextcloud-\([^"]\+\).zip.asc".*/\1/p' | sort --version-sort | tail -1)
+STABLEVERSION="nextcloud-$NCVERSION"
+```
+
 ## FAQ
 
 Keep asking questions so that we can add them here.