Update Readme with new diagramm and overview information

[klocke-io]

What would you like to be added:

Why is this needed / describe a real-world scenario:

How to categorize this?:

/kind enhancement
/priority 3

[gardener-ci-robot]

The Gardener project currently lacks enough active contributors to adequately respond to all issues.
This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 60d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 60d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as active with /lifecycle active
• Mark this issue as frozen with /lifecycle frozen
• Mark this issue as fresh with /remove-lifecycle stale
• Mark this issue as rotten with /lifecycle rotten
• Close this issue with /close

/lifecycle stale