docs(channels): explain dock commands

docs/concepts/session.md

@@ -53,6 +53,31 @@ If the same person contacts you from multiple channels, use
 `session.identityLinks` to link their identities so they share one session.
 </Tip>
 
+### Dock linked channels
+
+Dock commands let a user move the current direct-chat session's reply route to
+another linked channel without starting a new session. For example, with:
+
+```json5
+{
+  session: {
+    identityLinks: {
+      alice: ["telegram:123", "discord:456"],
+    },
+  },
+}
+```
+
+if Telegram sender `123` sends `/dock_discord`, OpenClaw keeps the current
+session context and stores Discord as the route for future replies from that
+session. The command updates the session delivery fields (`lastChannel`,
+`lastTo`, and `lastAccountId`) and persists them in the session store.
+
+Docking requires the source sender and target peer to appear in the same
+`session.identityLinks` group. If no linked target exists, the command replies
+with a setup hint and does not fall through to normal chat. Docking does not
+grant channel access or bypass channel allowlists.
+
 Verify your setup with `openclaw security audit`.
 
 ## Session lifecycle