Make documentation standalone and generalize examples

docs/interface/portal.md

@@ -18,7 +18,7 @@ API requests, responses and live updates through the connection.
     fluksio enroll <code>
     ```
 
-The CLI uses `https://hub.fluksio.com` by default. If you started the engine
+The CLI uses the built-in portal address by default. If you started the engine
 with `--data-dir` or `--global`, use the same option when enrolling. A running
 engine picks up the connection automatically; otherwise start it with
 `fluksio serve`.
@@ -65,12 +65,13 @@ removing them at the portal, or disconnecting, deletes them.
 ## Hooks and agents through the portal
 
 The portal also forwards a flow's hooks and the MCP endpoint, so they work
-without an inbound port:
+without an inbound port. Replace `portal.example.com` with your portal's API
+address in these examples:
 
 - A webhook or a served WebSocket:
-  `https://hub.fluksio.com/i/<instance-id>/hooks/<flow>/<url>/<secret>`,
+  `https://portal.example.com/i/<instance-id>/hooks/<flow>/<url>/<secret>`,
   with `wss://` for a socket.
-- An agent: `https://hub.fluksio.com/i/<instance-id>/mcp`, see
+- An agent: `https://portal.example.com/i/<instance-id>/mcp`, see
   [Agents over MCP](../code/agents.md).
 
 Through the portal a hook needs a [secret](../reference/node-types.md#http).