Release `haddock{,-api}-2.22.0`

This version will accompany ghc-8.6.2

Bump haddock-library to 1.7.0

The 1.6.1 release should've been a major bump, since types in
the `Documentation.Haddock.Parser.Monad` module changed. This version
makes that module internal (as it morally should be).

haddock-2.19.0.1, haddock-api-2.19.0.1, haddock-library-1.5.0.1

haddock-2.18.1, haddock-api-2.18.1, haddock-library-1.4.5

haddock-2.18.1, haddock-api-2.18.1, haddock-library-1.4.4

haddock-2.17.5, haddock-api-2.17.4 and haddock-library-1.4.3

haddock-2.17.4, haddock-api-2.17.4 and haddock-library-1.4.3

haddock-api 2.17.3.1

This is a patch-level release addressing
haskell#571

Release 2.17.3

Release 2.17.2