Fix broken links in the documentation.

PiperOrigin-RevId: 520657874
Change-Id: Idd01c40f87e0f2afcbd2d2bfd98fab95edc2371e

doc/unity.rst

@@ -140,7 +140,7 @@ When the user selects an MJCF file, the importer first loads
 the file in MuJoCo, saves it to a temporary location, and then processes the generated saved file.  This has several
 effects:
 
-- It validates the MJCF - we are guaranteed that the saved MJCF matches the `schema <CSchema>`_.
+- It validates the MJCF - we are guaranteed that the saved MJCF matches the :ref:`schema <CSchema>`.
 - It validates the assets (materials, meshes, textures) and imports these assets into Unity, as well as creating new
   material assets for geom RGBA specification.
 - It allows the importer to handle :ref:`\<include\> <include>` elements without replicating MuJoCo’s file-system
@@ -331,4 +331,4 @@ process, and uses Unity only for rendering.  In contrast, our plug-in relies on
 be possible to use our plug-in while an external process "drives" the simulation, for example by seting ``qpos``,
 calling ``mj_kinematics``, synchronizing the transforms, and then using Unity to render or compute game logic. In order
 to establish communication with an external process, you can use Unity's `ML-Agents
-<https://github.com/Unity-Technologies/ml-agents>`_ package.
+<https://github.com/Unity-Technologies/ml-agents>`_ package.