Add opened field to tcp-sockets.md docs (#13014)

This was introduced recently in our API.

content/workers/runtime-apis/tcp-sockets.md

@@ -75,6 +75,18 @@ export default {
 
 {{</definitions>}}
 
+### `SocketInfo`
+
+{{<definitions>}}
+
+- `remoteAddress` {{<type>}}string | null{{</type>}}
+  - The address of the remote peer the socket is connected to. May not always be set.
+
+- `localAddress` {{<type>}}string | null{{</type>}}
+  - The address of the local network endpoint for this socket. May not always be set.
+
+{{</definitions>}}
+
 ### `Socket`
 
 {{<definitions>}}
@@ -86,6 +98,9 @@ export default {
   - Returns the writable side of the TCP socket.
   - The `WritableStream` returned only accepts chunks of `Uint8Array` or its views.
 
+- `opened` {{<type>}}`Promise<SocketInfo>`{{</type>}}
+  - This promise is resolved when the socket connection is established and is rejected if the socket encounters an error.
+
 - `closed` {{<type>}}`Promise<void>`{{</type>}}
   - This promise is resolved when the socket is closed and is rejected if the socket encounters an error.