hackage-db.cabal: clarify the synopsis and description

Fixes #5.

Author: peti

hackage-db.cabal

@@ -7,21 +7,17 @@ maintainer:             Peter Simons <simons@cryp.to>
 homepage:               https://github.com/peti/hackage-db#readme
 bug-reports:            https://github.com/peti/hackage-db/issues
 category:               Distribution
-synopsis:               Access Hackage's package database via Data.Map
+synopsis:               Access cabal-install's Hackage database via Data.Map
 cabal-version:          >= 1.10
 build-type:             Simple
 tested-with:            GHC == 7.6.3, GHC == 7.8.4, GHC == 7.10.3
                       , GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.1
 
 description:
-  This is an early and mostly undocumented release of the 2.x version of
-  hackage-db that's intended mostly for experimenting with and testing of the
-  new API. Porting code from 1.x to 2.x is pretty simple, but if you do that at
-  this point, please expect minor details of this API to change in forthcoming
-  releases.
-  .
-  Check out https://github.com/peti/hackage-db/tree/master/example/ for a
-  collection of simple example programs that demonstrate how to use this code.
+  This library provides convenient access to the local copy of the Hackage
+  database that "cabal update" creates. Check out
+  https://github.com/peti/hackage-db/tree/master/example/ for a collection of
+  simple example programs that demonstrate how to use this code.
 
 source-repository head
   type: git