Updates CloudXR Teleoperation documentation with Known Issues. (#323)

# Description

Update CloudXR Teleoperation documentation with Known Issues.

## Type of change

- Documentation

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

docs/source/how-to/cloudxr_teleoperation.rst

@@ -49,6 +49,8 @@ This guide will walk you through how to:
 * :ref:`develop-xr-isaac-lab`, including how to :ref:`run-isaac-lab-with-xr`,
   :ref:`configure-scene-placement`, and :ref:`optimize-xr-performance`.
 
+As well as :ref:`xr-known-issues`.
+
 
 System Requirements
 -------------------
@@ -94,6 +96,13 @@ streaming the Isaac Lab simulation to a compatible XR device.
 Ensure that `Docker`_, `Docker Compose`_, and the `NVIDIA Container Toolkit`_ are installed on your
 Isaac Lab workstation as described in the Isaac Lab :ref:`deployment-docker`.
 
+Also ensure that your firewall allows connections to the ports used by CloudXR by running:
+
+.. code:: bash
+
+   sudo ufw allow 47998:48000,48005,48008,48012/udp
+   sudo ufw allow 48010/tcp
+
 There are two options to run the CloudXR Runtime Docker container:
 
 .. dropdown:: Option 1 (Recommended): Use Docker Compose to run the Isaac Lab and CloudXR Runtime
@@ -341,6 +350,11 @@ Back on your Apple Vision Pro:
 
 #. Teleoperate the simulated robot by moving your hands.
 
+   .. note::
+
+      See :ref:`teleoperation-imitation-learning` to learn how to record teleoperated demonstrations
+      and build teleoperation and imitation learning workflows with Isaac Lab.
+
 #. When you are finished with the example, click **Disconnect** to disconnect from Isaac Lab.
 
 
@@ -445,6 +459,24 @@ Optimize XR Performance
    cpu`` flag. This will cause Physics calculations to be done on the CPU, which may be reduce
    latency when only a single environment is present in the simulation.
 
+
+.. _xr-known-issues:
+
+Known Issues
+------------
+
+* ``[omni.kit.xr.system.openxr.plugin] Message received from CloudXR does not have a field called 'type'``
+
+  This error message can be safely ignored. It is caused by a deprecated, non-backwards-compatible
+  data message sent by the CloudXR Framework from Apple Vision Pro, and will be fixed in future
+  CloudXR Framework versions.
+
+* ``XR_ERROR_VALIDATION_FAILURE: xrWaitFrame(frameState->type == 0)`` when stopping AR Mode
+
+  This error message can be safely ignored. It is caused by a race condition in the exit handler for
+  AR Mode.
+
+
 ..
   References
 .. _`Apple Vision Pro`: https://www.apple.com/apple-vision-pro/