Add a comment to explain the HcPkg.recache trick
Add a comment to explain the HcPkg.recache trick

For supporting multi instance registrations on older GHC versions.

martinvlk/cabal,kolmodin/cabal,themoritz/cabal,thomie/cabal,sopvop/cabal,Heather/cabal,sopvop/cabal,martinvlk/cabal,garetxe/cabal,randen/cabal,lukexi/cabal,themoritz/cabal,Heather/cabal,kolmodin/cabal,lukexi/cabal,bennofs/cabal,gbaz/cabal,mydaum/cabal,edsko/cabal,thomie/cabal,sopvop/cabal,headprogrammingczar/cabal,themoritz/cabal,bennofs/cabal,headprogrammingczar/cabal,mydaum/cabal,edsko/cabal,randen/cabal,gbaz/cabal,garetxe/cabal