Ghost writing the docs with robots (#3951)

* First draft of general doc rewrite, by robots with help from @acolytec3

* Remove GitPOAP reference

* Add ToC, move package overview back to top

* Remove coverage report (use-/expressionless), complement ToC, replace outdated detailed-doc section with new config guide link, also redunda
nt getting-started section

* Sort both link section as well as package overview table alphabetically

* Add missing binarytree link references, fix broken package overview action links

* Rework branches section, some title optimizations

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Co-authored-by: Holger Drewes <[email protected]>

Author: acolytec3