docs: A pointer from each large topic to a resource

[Arkenan]

Some examples:

• Gasper basics from eth2book.
• Validator features from the specs.
• Slot lifecycle from the "anatomy of a slot" video.

[bomanaps]

Hello @Arkenan I would Love to work on this but to make sure I totally unnderstand this
Essentially, my job is to map major topics in the project to helpful resources, so that users can quickly understand or learn more about those topics by following the provided links.

If this is the case I have a few questions:

Structure and Format: How should the pointers be organized?
Content Guidelines: What level of detail is expected in the descriptions?
Resource Selection: Are there preferred sources or types of resources to link to?
Style and Tone: Should the documentation follow a specific style guide?
Examples and Templates: Are there existing examples I should model my work after?