Fix up API docs

[jml]

• Missing documentation for: Ed25519 (src/Crypto/Spake2/Groups/Ed25519.hs:62)
• Crypto.Spake2.Util: could not find link destinations for:
  • ByteArrayAccess
  • ByteArray
• Crypto.Spake2.Group: could not find link destinations for:
  • MonadRandom
  • ByteArray
  • CryptoFailable
  • ByteArrayAccess
• Crypto.Spake2.Math: could not find link destinations for: MonadRandom
• Crypto.Spake2.Groups: could not find link destinations for:
  • MonadRandom
  • ByteArray
  • CryptoFailable
  • ByteArrayAccess
• Warning: Crypto.Spake2: could not find link destinations for:
  • HashAlgorithm
  • concurrently
  • MonadRandom
  • Text

$ cabal haddock --builddir="$dir" --for-hackage --haddock-option=--hyperlinked-source
Warning: The package list for 'hackage.haskell.org' is 21 days old.
Run 'cabal update' to get the latest list of available packages.
Resolving dependencies...
Configuring spake2-0.4.0...
Running hscolour for spake2-0.4.0...
Preprocessing library for spake2-0.4.0..
Preprocessing executable 'haskell-spake2-interop-entrypoint' for spake2-0.4.0..
Preprocessing library for spake2-0.4.0..
Running Haddock on library for spake2-0.4.0..
Warning: The documentation for the following packages are not installed. No
links will be generated to these packages: async-2.1.1.1, basement-0.0.4,
cryptonite-0.24, foundation-0.0.17, hashable-1.2.6.1, memory-0.14.8,
mtl-2.2.1, mtl-compat-0.2.1.3, protolude-0.2, safe-0.3.15, stm-2.4.4.1,
text-1.2.2.2
Warning: --source-* options are ignored when --hyperlinked-source is enabled.
Haddock coverage:
 100% (  6 /  6) in 'Crypto.Spake2.Util'
 100% (  7 /  7) in 'Crypto.Spake2.Group'
 100% (  7 /  7) in 'Crypto.Spake2.Math'
 100% (  4 /  4) in 'Crypto.Spake2.Groups.IntegerGroup'
  80% (  4 /  5) in 'Crypto.Spake2.Groups.Ed25519'
  Missing documentation for:
    Ed25519 (src/Crypto/Spake2/Groups/Ed25519.hs:62)
  80% (  4 /  5) in 'Crypto.Spake2.Groups'
  Missing documentation for:
    Ed25519 (src/Crypto/Spake2/Groups/Ed25519.hs:62)
 100% ( 18 / 18) in 'Crypto.Spake2'
Warning: Crypto.Spake2.Util: could not find link destinations for:
    ByteArrayAccess ByteArray
Warning: Crypto.Spake2.Group: could not find link destinations for:
    MonadRandom ByteArray CryptoFailable ByteArrayAccess
Warning: Crypto.Spake2.Math: could not find link destinations for:
    MonadRandom
Warning: Crypto.Spake2.Groups: could not find link destinations for:
    MonadRandom ByteArray CryptoFailable ByteArrayAccess
Warning: Crypto.Spake2: could not find link destinations for:
    HashAlgorithm concurrently MonadRandom Text
Documentation created: dist-docs.c97ATW/doc/html/spake2-0.4.0-docs/index.html,
dist-docs.c97ATW/doc/html/spake2-0.4.0-docs/spake2.txt
Preprocessing executable 'haskell-spake2-interop-entrypoint' for spake2-0.4.0..
Documentation tarball created: dist-docs.c97ATW/spake2-0.4.0-docs.tar.gz