Improve README (#264)

## Description

This PR adds a hard-coded, slightly modified version of our operator READMEs, providing a better entry point into the Stackable ecosystem.

Author: Vladislav Supalov

.readme/static/borrowed/Icon_Stackable.svg

@@ -1,7 +1,96 @@
-# stackablectl
+<p align="center">
+  <img width="150" src="./.readme/static/borrowed/Icon_Stackable.svg" alt="Stackable Logo"/>
+</p>
 
-The documentation of `stackablectl` can be found in the [documentation of the Stackable Data Platform](https://docs.stackable.tech/stackablectl/stable/index.html).
+<h1 align="center">Stackablectl</h1>
 
-# TODOs
-* Check if CRD resources still exist when uninstalling the operators. If so warn the user.
-* Use Result instead of panic!() in multiple places
+[![Maintenance](https://img.shields.io/badge/Maintained%3F-yes-green.svg)](https://GitHub.com/stackabletech/druid-operator/graphs/commit-activity)
+[![PRs Welcome](https://img.shields.io/badge/PRs-welcome-green.svg)](https://docs.stackable.tech/home/stable/contributor/index.html)
+[![License OSL3.0](https://img.shields.io/badge/license-OSL3.0-green)](./LICENSE)
+
+[Documentation](https://docs.stackable.tech/stackablectl/stable/index.html) | [Stackable Data Platform](https://stackable.tech/) | [Platform Docs](https://docs.stackable.tech/) | [Discussions](https://github.com/orgs/stackabletech/discussions) | [Discord](https://discord.gg/7kZ3BNnCAF)
+
+This repository is the home of the CLI application `stackablectl`, which makes it convenient to setup and interact with any Stackable cluster.
+
+It is part of the Stackable Data Platform, a curated selection of the best open source data apps like Kafka, Druid, Trino or Spark, [all](#other-operators) working together seamlessly. Based on Kubernetes, it runs everywhere – [on prem or in the cloud](#supported-platforms).
+
+## Installation
+
+To install stackablectl, follow the instructions [in the docs](https://docs.stackable.tech/stackablectl/stable/installation.html).
+
+## Getting Started
+
+You can find a usage example in this [tutorial](https://docs.stackable.tech/stackablectl/stable/quickstart.html).
+
+## Documentation
+
+The stable documentation for this tool can be found [here](https://docs.stackable.tech/stackablectl/stable/installation.html).
+
+The documentation for all Stackable products can be found at [docs.stackable.tech](https://docs.stackable.tech).
+
+If you have a question about the Stackable Data Platform contact us via our [homepage](https://stackable.tech/) or ask a public questions in our [Discussions forum](https://github.com/orgs/stackabletech/discussions).
+
+
+## About The Stackable Data Platform
+
+This operator is written and maintained by [Stackable](https://www.stackable.tech) and it is part of a larger data platform.
+
+![Stackable Data Platform Overview](./.readme/static/borrowed/sdp_overview.png)
+
+Stackable makes it easy to operate data applications in any Kubernetes cluster.
+
+The data platform offers many operators, new ones being added continuously. All our operators are designed and built to be easily interconnected and to be consistent to work with.
+
+The [Stackable GmbH](https://stackable.tech/) is the company behind the Stackable Data Platform. Offering professional services, paid support plans and custom development.
+
+We love open-source!
+
+## Supported Platforms
+
+We develop and test our operators on the following cloud platforms:
+
+* AKS on Microsoft Azure
+* EKS on Amazon Web Services (AWS)
+* GKE on Google Cloud Platform (GCP)
+* [IONOS Cloud Managed Kubernetes](https://cloud.ionos.com/managed/kubernetes)
+* K3s
+* Kubernetes 1.23-1.26
+
+We are currently working to support:
+
+* OpenShift
+
+## Our Operators
+
+These are the operators that are currently part of the Stackable Data Platform:
+
+* [Stackable Operator for Apache Airflow](https://github.com/stackabletech/airflow-operator)
+* [Stackable Operator for Apache Druid](https://github.com/stackabletech/druid-operator)
+* [Stackable Operator for Apache HBase](https://github.com/stackabletech/hbase-operator)
+* [Stackable Operator for Apache Hadoop HDFS](https://github.com/stackabletech/hdfs-operator)
+* [Stackable Operator for Apache Hive](https://github.com/stackabletech/hive-operator)
+* [Stackable Operator for Apache Kafka](https://github.com/stackabletech/kafka-operator)
+* [Stackable Operator for Apache NiFi](https://github.com/stackabletech/nifi-operator)
+* [Stackable Operator for Apache Spark](https://github.com/stackabletech/spark-k8s-operator)
+* [Stackable Operator for Apache Superset](https://github.com/stackabletech/superset-operator)
+* [Stackable Operator for Trino](https://github.com/stackabletech/trino-operator)
+* [Stackable Operator for Apache ZooKeeper](https://github.com/stackabletech/zookeeper-operator)
+
+And our internal operators:
+
+* [Commons Operator](https://github.com/stackabletech/commons-operator)
+* [Listener Operator](https://github.com/stackabletech/listener-operator)
+* [OpenPolicyAgent Operator](https://github.com/stackabletech/opa-operator)
+* [Secret Operator](https://github.com/stackabletech/secret-operator)
+
+## Contributing
+
+Contributions are welcome. Follow our [Contributors Guide](https://docs.stackable.tech/home/stable/contributor/index.html) to learn how you can contribute.
+
+## License
+
+[Open Software License version 3.0](./LICENSE).
+
+## Support
+
+You can use this project under different licenses. Get started with the community edition! If you want professional support, [we offer subscription plans](https://stackable.tech/en/plans/).