new: [ntfy] add some minimal documentation on the ``ntfy`` command line and authentication options

ntfy/README.org

@@ -18,6 +18,49 @@ Any option from the help of [[https://docs.ntfy.sh/config/][ntfy]] can be used,
 
 To setup ~firebase~, there are some slight differences you can find here.
 
+*** Creating an admin account
+
+By default, =ntfy= doesn't provide any account nor permissions. This
+charm will enforce a different stance, and by default will not allow
+anything without permission.
+
+If you want to follow this route, you'll need to create an admin account:
+
+You need to attach to the ntfy container:
+
+#+begin_src sh
+docker exec -ti myproject_ntfy_1 sh
+#+end_src
+
+#+begin_src sh
+ntfy user add --role=admin admin
+#+end_src
+
+*** Adding user
+
+For listening topics
+
+#+begin_src sh
+ntfy user add myuser
+#+end_src
+
+To set access to topics
+
+#+begin_src sh
+ntfy access myuser mytopic read-only
+#+end_src
+
+*** Create a token for a user
+
+This allows to give a kind of secret key that is revokable. You would
+do this to distribute access to services that would need to send
+notification.
+
+To create a token from a user:
+
+#+begin_src sh
+ntfy token add admin
+#+end_src
 
 ** Connection with =Firebase=