Adds a quick start guide for quick installation and introduction (#370)

This PR adds a quickstart guide and various references to the setup
instructions for Isaac Lab

## 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 tests that prove my fix is effective or that my
feature works
- [X] 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

---------
Signed-off-by: Michael Gussert <michael@gussert.com>
Co-authored-by: Kelly Guo <kellyg@nvidia.com>

docs/index.rst

@@ -79,6 +79,7 @@ Table of Contents
    source/setup/ecosystem
    source/setup/installation/index
    source/setup/installation/cloud_installation
+   source/setup/quickstart
 
 .. toctree::
    :maxdepth: 3

docs/source/setup/installation/index.rst

+.. _isaaclab-installation-root:
+
 Local Installation
 ==================