Remove redundancy from Bitswap Discovery and Transfer

[SgtPooki]

The description in Discovery and Transfer seem to repeat the same information:

Discovery:

To find peers that have a file, a node running the Bitswap protocol first sends a request called a want-have to all the peers it is connected to. This want-have request contains the CID of the root block of the file (the root block is at the top of the DAG of blocks that make up the file). Peers that have the root block send a have response and are added to a session. Peers that don't have the block send a dont-have response. If none of the peers have the root block, Bitswap queries the Distributed Hash Table (DHT) to ask who can provide the root block.

Transfer:

Once peers have been added to a session, for each block that the client wants, Bitswap sends want-have to each session peer to find out which peers have the block. Peers respond with have or dont_have. Bitswap builds up a map of which nodes have and don't have each block. Bitswap sends want-block to peers that have the block, and they respond with the block itself. If no peers have the block, Bitswap queries the DHT to find providers who have the block.

The Transfer section could probably contain only the following:

Bitswap sends want-block to peers that have the block, and they respond with the block itself.

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[Annamarie2019]

@SgtPooki
So, basically, make sure that Transfer does not repeat anything from Discovery, yes? It sounds like the last sentence of Discovery would be better off in transfer, along with the sentence you suggest.

[Annamarie2019]

....I'll take this one.

[Annamarie2019]

Done. PR 1045. 1045 closed. Still working on correct PR workflow.

[Annamarie2019]

In review: PR #1051