Adds resources for learning Omniverse Kit (#343)

# Description

This MR adds a bunch of online resources and tutorials that users can
find useful for mastering Omniverse. This is not a complete list, but I
found them useful when I started.

## Type of change

- This change requires a documentation update

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./orbit.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

docs/source/how-to/index.rst

@@ -18,3 +18,4 @@ use Orbit. If you are new to Orbit, we recommend you start with the tutorials.
     save_camera_output
     draw_markers
     wrap_rl_env
+    master_omniverse

docs/source/how-to/master_omniverse.rst

+Mastering Omniverse for Robotics
+================================
+
+NVIDIA Omniverse offers a large suite of tools for 3D content workflows.
+There are three main components (relevant to robotics) in Omniverse:
+
+-  **USD Composer**: This is based on a novel file format (Universal Scene
+   Description) from the animation (originally Pixar) community that is
+   used in Omniverse
+-  **PhysX SDK**: This is the main physics engine behind Omniverse that
+   leverages GPU-based parallelization for massive scenes
+-  **RTX-enabled Renderer**: This uses ray-tracing kernels in NVIDIA RTX
+   GPUs for real-time physically-based rendering
+
+Of these, the first two require a deeper understanding to start working
+with Omniverse and its constituent applications (Isaac Sim and Orbit).
+
+The main things to learn:
+
+-  How to use the Composer GUI efficiently?
+-  What are USD prims and schemas?
+-  How do you compose a USD scene?
+-  What is the difference between references and payloads in USD?
+-  What is meant by scene-graph instancing?
+-  How to apply PhysX schemas on prims? What all schemas are possible?
+-  How to write basic operations in USD for creating prims and modifying
+   their attributes?
+
+
+Part 1: Using USD Composer
+--------------------------
+
+While several `video
+tutorials <https://www.youtube.com/@NVIDIA-Studio>`__ and
+`documentation <https://docs.omniverse.nvidia.com/>`__ exist
+out there on NVIDIA Omniverse, going through all of them would take an
+extensive amount of time and effort. Thus, we have curated these
+resources to guide you through using Omniverse, specifically for
+robotics.
+
+Introduction to Omniverse and USD
+
+-  `What is NVIDIA Omniverse? <https://youtu.be/dvdB-ndYJBM>`__
+-  `What is the USD File Type? \| Getting Started in NVIDIA Omniverse <https://youtu.be/GOdyx-oSs2M>`__
+-  `What Makes USD Unique in NVIDIA Omniverse <https://youtu.be/o2x-30-PTkw>`__
+
+Using Omniverse USD Composer
+
+-  `Introduction to Omniverse USD Composer <https://youtu.be/_30Pf3nccuE>`__
+-  `Navigation Basics in Omniverse USD Composer <https://youtu.be/kb4ZA3TyMak>`__
+-  `Lighting Basics in NVIDIA Omniverse USD Composer <https://youtu.be/c7qyI8pZvF4>`__
+-  `Rendering Overview in NVIDIA Omniverse USD Composer <https://youtu.be/dCvq2ZyYmu4>`__
+
+Materials and MDL
+
+-  `Five Things to Know About Materials in NVIDIA Omniverse <https://youtu.be/C0HmcQXaENc>`__
+-  `How to apply materials? <https://docs.omniverse.nvidia.com/materials-and-rendering/latest/materials.html%23applying-materials>`__
+
+Omniverse Physics and PhysX SDK
+
+-  `Basics - Setting Up Physics and Toolbar Overview <https://youtu.be/nsJ0S9MycJI>`__
+-  `Basics - Demos Overview <https://youtu.be/-y0-EVTj10s>`__
+-  `Rigid Bodies - Mass Editing <https://youtu.be/GHl2RwWeRuM>`__
+-  `Materials - Friction Restitution and Defaults <https://youtu.be/oTW81DltNiE>`__
+-  `Overview of Simulation Ready Assets Physics in Omniverse <https://youtu.be/lFtEMg86lJc>`__
+
+Importing assets
+
+-  `Omniverse Create - Importing FBX Files \| NVIDIA Omniverse Tutorials <https://youtu.be/dQI0OpzfVHw>`__
+-  `Omniverse Asset Importer <https://docs.omniverse.nvidia.com/extensions/latest/ext_asset-importer.html>`__
+-  `Isaac Sim URDF impoter <https://docs.omniverse.nvidia.com/isaacsim/latest/ext_omni_isaac_urdf.html>`__
+
+The above mainly introduces how to use the USD Composer and its
+functionalities to do operations using the UI. However, many developers,
+who want to do scripting, need to also understand the APIs of Omniverse.
+This requires understanding how developments happen within the Omniverse
+team since many applications provide their own set of tooling around
+Omniverse, often specialized for their particular use cases.
+
+Part 2: Scripting in Omniverse
+------------------------------
+
+As learned from the videos earlier, USD is the main file format
+Omniverse operates with. So naturally, the APIs (from OpenUSD) for
+modifying USD are at the core of Omniverse. Most of the time, we will
+work with Python scripting and use the Python bindings to different
+APIs.
+
+.. note::
+
+   While Isaac Sim and Orbit try to "relieve" users from understanding
+   the core USD concepts and APIs, understanding these basics still
+   helps a lot once you start diving inside the codebase and modifying
+   it for your own application.
+
+Before diving into USD scripting, it is good to get acquainted with the
+terminologies used in USD. We recommend the following `introduction to
+USD basics <https://www.sidefx.com/docs/houdini/solaris/usd.html>`__ by
+Houdini, which is a 3D animation software.
+Make sure to go through the following sections:
+
+-  `Quick example <https://www.sidefx.com/docs/houdini/solaris/usd.html%23quick-example>`__
+-  `Attributes and primvars <https://www.sidefx.com/docs/houdini/solaris/usd.html%23attrs>`__
+-  `Composition <https://www.sidefx.com/docs/houdini/solaris/usd.html%23compose>`__
+-  `Schemas <https://www.sidefx.com/docs/houdini/solaris/usd.html%23schemas>`__
+-  `Instances <https://www.sidefx.com/docs/houdini/solaris/usd.html%23instancing>`__
+   and `Scene-graph Instancing <https://openusd.org/dev/api/_usd__page__scenegraph_instancing.html>`__
+
+As a test of understanding, make sure you can answer the following:
+
+-  What are prims? What is meant by a prim path in a stage?
+-  How are attributes related to prims?
+-  How are schemas related to prims?
+-  What is the difference between attributes and schemas?
+-  What is asset instancing?
+
+Part 3: More Resources
+----------------------
+
+- `Omniverse Glossary of Terms <https://docs.omniverse.nvidia.com/isaacsim/latest/common/glossary-of-terms.html>`__
+- `Omniverse Code Samples <https://docs.omniverse.nvidia.com/dev-guide/latest/programmer_ref.html>`__
+- `PhysX Collider compatibility <https://docs.omniverse.nvidia.com/extensions/latest/ext_physics/rigid-bodies.html#collidercompatibility>`__
+- `PhysX limitations <https://docs.omniverse.nvidia.com/isaacsim/latest/features/physics/physX_limitations.html>`__
+- To learn more about PhysX, please always check their `official documentation <https://nvidia-omniverse.github.io/PhysX/physx/>`__.

docs/source/refs/troubleshooting.rst

 Tricks and Troubleshooting
 ==========================
 
+.. note::
+
+    The following lists some of the common tricks and troubleshooting methods that we use in our common workflows.
+    Please also check the `troubleshooting page on Omniverse
+    <https://docs.omniverse.nvidia.com/kit/docs/kit-manual/latest/guide/linux_troubleshooting.html>`__ for more
+    assistance.
+
+
 Using CPU Scaling Governor for performance
 ------------------------------------------