Cleans up instructions for custom dependency installation (#621)

# Description

This MR mainly fixes the documentation to make instructions clearer. The
script was unclear about where the workspace path needs to be and how it
can be resolved. The MR makes sure these cases are dealt and reported
correctly.

## Type of change

- This change requires a documentation update

## 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
- [ ] 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/setup/developer.rst

@@ -191,29 +191,46 @@ standalone applications.
 Extension Dependency Management
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-Certain extensions may have dependencies which need to be installed before the extension can be run.
-While Python dependencies can be expressed via the ``INSTALL_REQUIRES`` array in ``setup.py``, we need
-a separate installation pipeline to handle non-Python dependencies. We have therefore created
-an additional setup procedure, ``python tools/install_deps.py {dep_type} {extensions_dir}``, which scans the ``extension.toml``
-file of the directories under the ``{extensions_dir}`` (such as ``${ISAACLAB_PATH}/source/extensions``) for ``apt`` and ``rosdep`` dependencies.
+Certain extensions may have dependencies which require installation of additional packages before the extension
+can be used. While Python dependencies are handled by the `setuptools <https://setuptools.readthedocs.io/en/latest/>`__
+package and specified in the ``setup.py`` file, non-Python dependencies such as `ROS <https://www.ros.org/>`__
+packages or `apt <https://en.wikipedia.org/wiki/APT_(software)>`__ packages are not handled by setuptools.
+To handle these dependencies, we have created an additional setup procedure described in the next section.
 
-This example ``extension.toml`` has both ``apt_deps`` and ``ros_ws`` specified, so both
-``apt`` and ``rosdep`` packages will be installed if ``python tools/install_deps.py all ${ISAACLAB_PATH}/source/extensions``
-is passed:
+There are two types of dependencies that can be specified in the ``extension.toml`` file
+under the ``isaac_lab_settings`` section:
+
+1. **apt_deps**: A list of apt packages that need to be installed. These are installed using the
+   `apt <https://ubuntu.com/server/docs/package-management>`__ package manager.
+2. **ros_ws**: The path to the ROS workspace that contains the ROS packages. These are installed using
+   the `rosdep <https://docs.ros.org/en/humble/Tutorials/Intermediate/Rosdep.html>`__ dependency manager.
+
+As an example, the following ``extension.toml`` file specifies the dependencies for the extension:
 
 .. code-block:: toml
 
-   [isaaclab_settings]
-   apt_deps = ["example_package"]
-   ros_ws = "path/from/extension_root/to/ros_ws"
+   [isaac_lab_settings]
+   # apt dependencies
+   apt_deps = ["libboost-all-dev"]
 
-From the ``apt_deps`` in the above example, the package ``example_package`` would be installed via ``apt``.
-From the ``ros_ws``, a ``rosdep install --from-paths {ros_ws}/src --ignore-src`` command will be called.
-This will install all the `ROS package.xml dependencies <https://docs.ros.org/en/humble/Tutorials/Intermediate/Rosdep.html>`__
-in the directory structure below. Currently the ROS distro is assumed to be ``humble``.
+   # ROS workspace
+   # note: if this path is relative, it is relative to the extension directory's root
+   ros_ws = "/home/user/catkin_ws"
 
-``apt`` deps are automatically installed this way during the build process of the ``Dockerfile.base``,
-and ``rosdep`` deps during the build process of ``Dockerfile.ros2``.
+These dependencies are installed using the ``install_deps.py`` script provided in the ``tools`` directory.
+To install all dependencies for all extensions, run the following command:
+
+.. code-block:: bash
+
+   # execute from the root of the repository
+   # the script expects the type of dependencies to install and the path to the extensions directory
+   # available types are: 'apt', 'rosdep' and 'all'
+   python tools/install_deps.py all ${ISAACLAB_PATH}/source/extensions
+
+.. note::
+   Currently, this script is automatically executed during the build process of the ``Dockerfile.base``
+   and ``Dockerfile.ros2``. This ensures that all the 'apt' and 'rosdep' dependencies are installed
+   before building the extensions respectively.
 
 
 Standalone applications