[Task]: Improve project documentation on apache-beam pypi page.

[tvalentyn]

What needs to happen?

Current project summary is a very short paragraph: https://pypi.org/project/apache-beam/. We could add more content and useful pointers to that page, perhaps similar to https://pypi.org/project/scipy/.

Issue Priority

Priority: 3 (nice-to-have improvement)

Issue Components

• [X] Component: Python SDK
• [ ] Component: Java SDK
• [ ] Component: Go SDK
• [ ] Component: Typescript SDK
• [ ] Component: IO connector
• [ ] Component: Beam YAML
• [ ] Component: Beam examples
• [ ] Component: Beam playground
• [ ] Component: Beam katas
• [x] Component: Website
• [ ] Component: Spark Runner
• [ ] Component: Flink Runner
• [ ] Component: Samza Runner
• [ ] Component: Twister2 Runner
• [ ] Component: Hazelcast Jet Runner
• [ ] Component: Google Cloud Dataflow Runner