Add package metadata

Author: ollef

package.yaml

@@ -11,8 +11,8 @@ extra-source-files:
 - CHANGELOG.md
 
 # Metadata used when publishing your package
-# synopsis:            Short description of your package
-# category:            Web
+synopsis:            Elm syntax and pretty-printing
+category:            Elm, Compiler, Language
 
 # To avoid duplicated efforts in documentation and dealing with the
 # complications of embedding Haddock markup inside cabal files, it is