Hi.

I have fantastic news. We are growing! 🐈 Together with this, our documentation grows and we have newer needs and requirements. 

We currently only publish documentation for our app releases. 
 - https://airflow.apache.org/docs/stable/

But our community is also working on other products that have a different release cycle, use case, docs build tool and needs
- Production Docker image: https://hub.docker.com/r/apache/airflow
- REST API: https://airflow.readthedocs.io/en/latest/stable-rest-api-ref.html (it has a separate version number, so a version index could be helpful. We can also set the version to the application version)
- Backport/provider packages: https://github.com/apache/airflow/tree/master/backport_packages
- Helm Chart: https://github.com/apache/airflow/tree/master/chart
- [API Clients for Apache Airflow](https://github.com/apache/airflow/issues/10176)
  - Go: https://github.com/apache/airflow-client-go 
  - Python: https://github.com/apache/airflow-client-python
  - Java: https://github.com/apache/airflow-client-java
  - Javascript: https://github.com/apache/airflow-client-javascript
- Apache Airflow on K8S Operator: https://github.com/apache/airflow-on-k8s-operator

and other: https://github.com/apache/airflow/issues/10550, https://github.com/apache/airflow/issues/10552

I think it is worth considering how we want to inform users about these products on our website.  

One solution is to create an index at: `https://airflow.apache.org/docs/` (currently there is a redirection to the latest stable version of the documentation), which will refer you to separate documentation for each product.
It will look similar to the examples:
https://mc-stan.org/
https://cloud.google.com/sql/docs/
https://www.terraform.io/docs/

An alternative solution is moving all documentations to our app documentation:
https://github.com/apache/airflow/pull/11136
https://github.com/apache/airflow/pull/10998

What is our plan for this documentation? Do we need to standardize our documentation building tools? What requirements does each documentation have, e.g. do we always need versioning? 
CC: @kaxil @potiuk 

docs/build_docs.py
"""Get list of all available packages to build."""
    provider_package_names = [provider['package-name'] for provider in ALL_PROVIDER_YAMLS]
    return ["apache-airflow", *provider_package_names, "apache-airflow-providers"]
def _get_parser():
    available_packages_list = " * " + "\n * ".join(get_available_packages())
    parser = argparse.ArgumentParser(
        description='Builds documentation and runs spell checking',
        epilog=f"List of supported documentation packages:\n{available_packages_list}" "",
    )
    parser.formatter_class = argparse.RawTextHelpFormatter
    parser.add_argument(
        '--disable-checks', dest='disable_checks', action='store_true', help='Disables extra checks'
    )
    parser.add_argument(
        "--package-filter",
        action="append",
        help=(
            "Filter specifying for which packages the documentation is to be built. Wildcard are supported."
        ),
    )
    parser.add_argument('--docs-only', dest='docs_only', action='store_true', help='Only build documentation')
    parser.add_argument(
        '--spellcheck-only', dest='spellcheck_only', action='store_true', help='Only perform spellchecking'
    )
    return parser
def build_docs_for_packages(