[docs] list of doc improvements

[lanzafame]

List of doc improvements mentioned in #1 that will potentially (linking so they don't get lost) get incorporated into the next iteration:

• https://github.com/libp2p/go-libp2p-core/pull/1/files#r276048081
• https://github.com/libp2p/go-libp2p-core/pull/1/files#r276049519
• https://github.com/libp2p/go-libp2p-core/pull/1/files#r276052657
• https://github.com/libp2p/go-libp2p-core/pull/1/files#r276055055
• https://github.com/libp2p/go-libp2p-core/pull/1/files#r276055848
• Absorb go-libp2p abstractions and core types into this module #1 (review)
• https://github.com/libp2p/go-libp2p-core/pull/1/files#r276497226

[raulk]

@yusefnapora let's tag-team on this, if you have cycles.

[raulk]

@lanzafame is enumerating a few places where clarifications are needed. But the goal is larger. Rewriting all godocs is on the table. We want excellent, intuitive, clear, precise godocs that minimise the need to rely on external docs.