Improvement: Text and picture in building blocks concept are not complete and well documented

### What

In the following picture there is no legend what the line styles means. Additionally the text does not describe any of the boxes and there are no links to the sections where are they described.

Additionally this picture does not show any all of the blocks defined in the docs_as-code meta modell.

https://eclipse-score.github.io/process_description/main/general_concepts/score_building_blocks_concept.html

### How

_No response_

### Estimates for realization

5 md

### Category

- [ ] Affects Detailed Design

### Requirements / Architecture

- [x] Requirements / Architecture are not affected by this change?