Cabal revisions of hdocs-0.5.1.0

Hackage metadata revisions edit the .cabal file after upload; each diff below is one revision.

 name:                hdocs
 version:             0.5.1.0
+x-revision: 1
 synopsis:            Haskell docs tool
 description:
   Tool and library to get docs for installed packages and source files.
       haddock-api >= 2.17.0 && < 2.18.0,
       haddock-library == 1.4.*
   if impl(ghc < 8.0)
+    -- See https://github.com/mvoidex/hdocs/issues/6
+    build-depends: haddock-api >= 2.17.0
+
     build-depends:
       ghc >= 7.8.1 && < 8.0.0,
       haddock-api >= 2.16.0 && < 2.17.0,