Reorganize chapter hierarchy

We have to many main chapters, some could be sub-chapters. We should reorganize the chapter structure.

Example:

1. Developer Guidelines (everything until release)
2. Operational Guidelines (everything after release)

Policy recommendations serve as starting points for each guideline. Software Quality is and should be the overarching topic

Zwischenstand

- Chapters  
	- /onboarding.md @FE  
	- /style-guides.md D; @FE => @SUB  
		- Generalisieren; "For Specific Programming Languages" reduziere zu inline Aufzählung mit direkten links  
	- /documentation.md; D; @FE => @SUB; REWORK  
		- "doc-sprints" => onboarding  
		- "software-architecture", streiche examples  
		- "API Documentation"; interne: sprachspezifisch; REST API nach OpenAPI (reduziere beispiele zu inline Aufzählung mit direkten links)  
		- "Admin Documentation";  
	- /version-control.md; D; @FE => @SUB  
		- chose a flow and document it: examples git flow, gitlab flow, github flow
		- should be merged with "release management"
	- /bug-tracking.md; D/O; @SUB  
		- Wie wollen wir Kapitel, die D und O betreffen organisieren? TODO: diskutieren am Beispiel von bug-tracking
	- /logging.md; D/O; @SUB  
	- /software-tests.md; D; @SUB  
	- /design-architecture.md  D; @SUB
	- /security-and-compliance.md  D/O; @SUB 
	   - should be split into D&O?
	- /build.md  D; @FE => @SUB  
	   - examples from 12.1 can be removed, we want to document what 
	     we want to use in future, and not what was used in the past
	- /ci-cd.md  D; @SUB
	- /maintenance.md  O; @FE => @SUB  
	   - remove puppet (optionlly add link in onboarding)
	   - icinga is FE specific, possibly write some notes on openITC
	- /release-management.md; D; @SUB 
	- /code-quality.md  D; @SUB 
	   - workflow belongs somehow to version control chapter (gitlab-flow)
	- /intellectual-property.md  D; @SUB
	- /sustainability.md  D/O; @SUB
	- /links.md  
	- /qualification.md => Onboarding
	   - bildungsurlaub => onboarding

- D: Developer Guidelines  
- O: Operational Guidelines

@SUB genereller sub part
@FE fe spezifisch
@FE => @SUB  : umbauen von fe spezifisch nach sub generisch