Document all features

[guillaumemichel]

There is a lack of feature of documentation in go-libp2p-kad-dht, which make it hard to keep the IPFS DHT spec up-to-date, and generally hard to understand what happens in the DHT implementation. We should document all features we are implementing from the start. The feature documentation should ideally live in the same repository, or alternatively on a spec/doc repository that must be kept up-to-date (e.g documentation should be added BEFORE merging the PR).

We should document the design of this implementation thoroughly.

In addition, as the Kademlia paper doesn't go much into the implementation details, we need to document them:

• #47
• #46
• #45
• #44
• #22
• probe-lab/zikade#40
• #3
• #2

We should also document all non-standard Kademlia items that we add to the libp2p/IPFS implementation, for examples:

• #53
• #49
• probe-lab/zikade#39
• #43
• #38
• #31
• probe-lab/zikade#42
• #26
• #25
• #23
• probe-lab/zikade#41