bbb-pre-install.sh: add 'apt-get update' after adding docker repository.

bbb-pre-install.sh

@@ -690,6 +690,26 @@ EOF
 fi
 
 
+echononl "Update repositories.."
+apt-get update > "$log_file" 2>&1
+if [[ $? -ne 0 ]]; then
+   echo_failed
+   error "$(cat "$log_file")"
+
+   echononl "continue anyway [yes/no]: "
+   read OK
+   OK="$(echo "$OK" | tr '[:upper:]' '[:lower:]')"
+   while [[ "$OK" != "yes" ]] && [[  "$OK" != "no" ]] ; do
+      echononl "Wrong entry! - repeat [yes/no]: "
+      read OK
+   done
+   [[ $OK = "yes" ]] || fatal "Interrupted by user."
+
+else
+   echo_ok
+fi
+
+
 echononl "Install docker-ce .."
 
 if $(dpkg -s  docker-ce> /dev/null 2>&1 ) ; then