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
current_packages: List[str], docs_only: bool, spellcheck_only: bool
) -> Tuple[Dict[str, List[DocBuildError]], Dict[str, List[SpellingError]]]:
    """Builds documentation for single package and returns errors"""
    all_build_errors: Dict[str, List[DocBuildError]] = defaultdict(list)
    all_spelling_errors: Dict[str, List[SpellingError]] = defaultdict(list)
    for package_name in current_packages:
        print("#" * 20, package_name, "#" * 20)
        builder = AirflowDocsBuilder(package_name=package_name)
        builder.clean_files()
        if not docs_only:
            spelling_errors = builder.check_spelling()
            if spelling_errors:
                all_spelling_errors[package_name].extend(spelling_errors)
        if not spellcheck_only:
            docs_errors = builder.build_sphinx_docs()
            if docs_errors:
                all_build_errors[package_name].extend(docs_errors)
    return all_build_errors, all_spelling_errors
def display_packages_summary(
    build_errors: Dict[str, List[DocBuildError]], spelling_errors: Dict[str, List[SpellingError]]
):
    """Displays a summary that contains information on the number of errors in each packages"""
    packages_names = {*build_errors.keys(), *spelling_errors.keys()}
    tabular_data = [
        {
            "Package name": package_name,
            "Count of doc build errors": len(build_errors.get(package_name, [])),
            "Count of spelling errors": len(spelling_errors.get(package_name, [])),