[Documentation] "Learn" section

### Relevant documentation

Other

### Problem description (optional)

As development gets more complex more knowledge is required.
Currently we do not provide any information on how to learn to work with our reference architecture templates.
We should provide some help here about core concepts, technologies and so on.

We had a link collection in the old internal documentation so we would like to reimplement this for the new public documentation.

### Desired solution

Add a section "Learn" with information about learning the concepts and technologies behind our reference architecture.

This could e.g. be a collection of useful links to articles or videos grouped by different development topics.

Also a "Cookbook" would be handy to provide suggestions e.g. for dependencies when having a specific development requirement (like integrating maps, ...), e.g. some where deleted (https://github.com/it-at-m/refarch-templates/pull/865)
- Apache commons libraries
- `hibernate-jpamodelgen`

### Additional context (optional)

_No response_

### No duplicate

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