Fix docs build: pin warp intersphinx to /stable/

https://nvidia.github.io/warp/objects.inv now returns 404; the inventory
moved under /stable/ (and /latest/). With warnings treated as errors, the
broken intersphinx fetch fails the docs build on every PR.

Repro: any recent CI run on develop, e.g.
https://github.com/isaac-sim/IsaacLab/actions/runs/25533637651/job/74955918336

  WARNING: failed to reach any of the inventories with the following issues:
  intersphinx inventory 'https://nvidia.github.io/warp/objects.inv' not
    fetchable due to 404 Client Error: Not Found
  build finished with problems, 1 warning (with warnings treated as errors).

Author: hujc7

docs/conf.py

@@ -140,7 +140,8 @@
     "torch": ("https://docs.pytorch.org/docs/2.11/", None),
     "isaacsim": ("https://docs.isaacsim.omniverse.nvidia.com/6.0.0/py/", None),
     "gymnasium": ("https://gymnasium.farama.org/", None),
-    "warp": ("https://nvidia.github.io/warp/", None),
+    # NOTE: pinned to /stable/ because /objects.inv at the root currently 404s
+    "warp": ("https://nvidia.github.io/warp/stable/", None),
     "omniverse": ("https://docs.omniverse.nvidia.com/dev-guide/latest", None),
 }
 

source/isaaclab/changelog.d/jichuanh-fix-warp-intersphinx.rst

@@ -0,0 +1,5 @@
+Fixed
+^^^^^
+
+* Fixed Sphinx docs build failing due to ``https://nvidia.github.io/warp/objects.inv`` returning 404.
+  Pinned the ``warp`` intersphinx mapping to ``/stable/``, which is where the inventory now lives.