Improve delete-account script and documentation

docs/delete-account.md

 Delete User Cccount
 -------------------
 
-1. Delete email account and data
-    - login to mail.$DOMAIN
-    - click on domain list
-    - select the correct domain
-    - search for the username on the top right
-    - delete the correct account
-
-2. delete nextcloud account
+1. Delete email account, Nextcloud account and all data
     - `ssh user@$DOMAIN`
     - `cd /mnt/repo-base/`
-    - `sudo docker-compose exec -u www-data nextcloud php occ user:delete user@$DOMAIN`
+    - `sudo ./scripts/delete-account $USER`
 
-4. onlyoffice data
+2. onlyoffice data
     - go to [https://office.$DOMAIN/products/people/#sortorder=ascending](https://office.$DOMAIN/products/people/#sortorder=ascending)
     - search for the username
     - click on the arrow at the far right and press "Delete profile"

scripts/delete-account.sh

@@ -5,8 +5,19 @@ source /mnt/repo-base/scripts/base.sh
 
 ACCOUNT=$1
 
-docker-compose exec -T -u www-data nextcloud php occ user:delete "$ACCOUNT"
+if ! docker-compose exec -T -u www-data nextcloud php occ user:info "$ACCOUNT" | grep "$ACCOUNT" --quiet; then
+    echo "Error: The account $ACCOUNT does not exist"
+    exit
+fi
 
-docker-compose exec -T postfixadmin /postfixadmin/scripts/postfixadmin-cli mailbox delete "$ACCOUNT"
+echo "Please confirm to delete the user account $ACCOUNT including all data. This is not reversible."
+read -r -p "[y/N] " response
+if [[ $response =~ ^([yY][eE][sS]|[yY])$ ]]; then
+    echo "Deleting Nextcloud account"
+    docker-compose exec -T -u www-data nextcloud php occ user:delete "$ACCOUNT"
 
-# TODO: delete onlyoffice account???
+    echo "Deleting email account"
+    docker-compose exec -T postfixadmin /postfixadmin/scripts/postfixadmin-cli mailbox delete "$ACCOUNT"
+
+    # TODO: delete onlyoffice account???
+fi