improve haddock coverage

[vu3rdd]

I tried building with Documentation: True in ~/.cabal/config and found the reported haddock coverage maps to be quite minimal, so this is one area to work on.

[vu3rdd]

Current status of haddock coverage:

Haddock coverage:
  50% (  4 /  8) in 'Transit.Internal.Crypto'
  Missing documentation for:
    Module header
    PlainText (src/Transit/Internal/Crypto.hs:22)
    CipherText (src/Transit/Internal/Crypto.hs:23)
    CryptoError (src/Transit/Internal/Crypto.hs:25)
   0% (  0 /  8) in 'Transit.Internal.Messages'
  Missing documentation for:
    Module header
    TransitMsg (src/Transit/Internal/Messages.hs:119)
    Ability (src/Transit/Internal/Messages.hs:106)
    AbilityV1 (src/Transit/Internal/Messages.hs:29)
    Hint (src/Transit/Internal/Messages.hs:42)
    ConnectionHint (src/Transit/Internal/Messages.hs:65)
    Ack (src/Transit/Internal/Messages.hs:92)
    TransitAck (src/Transit/Internal/Messages.hs:136)
  33% (  5 / 15) in 'Transit.Internal.Network'
  Missing documentation for:
    Module header
    buildDirectHints (src/Transit/Internal/Network.hs:81)
    sendBuffer (src/Transit/Internal/Network.hs:122)
    recvBuffer (src/Transit/Internal/Network.hs:125)
    closeConnection (src/Transit/Internal/Network.hs:128)
    TCPEndpoint (src/Transit/Internal/Network.hs:98)
    tcpListener (src/Transit/Internal/Network.hs:61)
    startServer (src/Transit/Internal/Network.hs:131)
    startClient (src/Transit/Internal/Network.hs:152)
    CommunicationError (src/Transit/Internal/Network.hs:137)
  15% (  3 / 20) in 'Transit.Internal.Peer'
  Missing documentation for:
    Module header
    makeSenderHandshake (src/Transit/Internal/Peer.hs:48)
    makeReceiverHandshake (src/Transit/Internal/Peer.hs:55)
    makeSenderRecordKey (src/Transit/Internal/Peer.hs:72)
    makeReceiverRecordKey (src/Transit/Internal/Peer.hs:76)
    senderFileOfferExchange (src/Transit/Internal/Peer.hs:142)
    sendOffer (src/Transit/Internal/Peer.hs:113)
    sendMessageAck (src/Transit/Internal/Peer.hs:137)
    receiveMessageAck (src/Transit/Internal/Peer.hs:128)
    senderHandshakeExchange (src/Transit/Internal/Peer.hs:180)
    receiverHandshakeExchange (src/Transit/Internal/Peer.hs:195)
    sendTransitMsg (src/Transit/Internal/Peer.hs:99)
    decodeTransitMsg (src/Transit/Internal/Peer.hs:107)
    sendGoodAckMessage (src/Transit/Internal/Peer.hs:217)
    receiveAckMessage (src/Transit/Internal/Peer.hs:209)
    receiveWormholeMessage (src/Transit/Internal/Peer.hs:166)
    sendWormholeMessage (src/Transit/Internal/Peer.hs:171)
  80% (  4 /  5) in 'Transit.Internal.Pipeline'
  Missing documentation for:
    Module header

src/Transit/Internal/FileTransfer.hs:48:22: warning: [-Wunused-matches]
    Defined but not used: ‘peerAbilities’
   |
48 |       Right (Transit peerAbilities peerHints) -> do
   |                      ^^^^^^^^^^^^^

src/Transit/Internal/FileTransfer.hs:82:33: warning: [-Wunused-matches]
    Defined but not used: ‘peerAbilities’
   |
82 | receiveFile conn appid (Transit peerAbilities peerHints) = do
   |                                 ^^^^^^^^^^^^^
  25% (  1 /  4) in 'Transit.Internal.FileTransfer'
  Missing documentation for:
    Module header
    receiveFile (src/Transit/Internal/FileTransfer.hs:81)
    MessageType (src/Transit/Internal/FileTransfer.hs:25)
  30% (  3 / 10) in 'Transit'
  Missing documentation for:
    receiveFile (src/Transit/Internal/FileTransfer.hs:81)
    MessageType (src/Transit/Internal/FileTransfer.hs:25)
    sendOffer (src/Transit/Internal/Peer.hs:113)
    receiveMessageAck (src/Transit/Internal/Peer.hs:128)
    sendMessageAck (src/Transit/Internal/Peer.hs:137)
    decodeTransitMsg (src/Transit/Internal/Peer.hs:107)
    CommunicationError (src/Transit/Internal/Network.hs:137)
Warning: Transit.Internal.Crypto: could not find link destinations for:
    Key Nonce Either ByteString Eq == Bool /= Show showsPrec Int ShowS show String showList Text Exception toException SomeException fromException Maybe displayException
Warning: Transit.Internal.Messages: could not find link destinations for:
    Text Eq == Bool /= Show showsPrec Int ShowS show String showList Generic from Rep to * FromJSON parseJSON Value Parser parseJSONList ToJSON toJSON toEncoding Encoding toJSONList toEncodingList D1 MetaData False :+: C1 MetaCons PrefixI S1 MetaSel Nothing Maybe Symbol NoSourceUnpackedness NoSourceStrictness DecidedLazy Rec0 True :*: Just U1 Double Word16 Ord compare Ordering < <= > >= max min
Warning: Transit.Internal.Network: could not find link destinations for:
    PortNumber IO ByteString Int Socket Eq == Bool /= Show showsPrec ShowS show String showList Text Exception toException SomeException fromException Maybe displayException
Warning: Transit.Internal.Peer: could not find link destinations for:
    Key ByteString Maybe Side EncryptedConnection PortNumber IO Either Text FilePath Offer ByteString
Warning: Transit.Internal.Pipeline: could not find link destinations for:
    FilePath Key Text Int Monad ByteString
Warning: Transit.Internal.FileTransfer: could not find link destinations for:
    EncryptedConnection AppID FilePath IO putStrLn Text Eq == Bool /= Show showsPrec Int ShowS show String showList
Warning: Transit: could not find link destinations for:
    EncryptedConnection AppID FilePath IO putStrLn Text Eq == Bool /= Show showsPrec Int ShowS show String showList Offer Either ByteString Exception toException SomeException fromException Maybe displayException
Documentation created: