Explicitly list embedded files in cabal file

Needed for cabal to know it needs to rebuild stuff when they change. In 0ded0ff I expected that haskell/cabal#6889 would make this work even for wildcards but this is not the case. A proper fix for haskell/cabal#4746 is probably needed instead.

Author: georgefst

haskell/monpad.cabal

@@ -5,9 +5,11 @@ license:             BSD-3-Clause
 author:              George Thomas
 maintainer:          [email protected]
 extra-source-files:
-    rsc/*.css
-    rsc/*.js
-    rsc/*.dhall
+    rsc/app.css
+    rsc/common.css
+    rsc/elm.js
+    rsc/main.js
+    rsc/default.dhall
 
 flag release
     Description: Distributable build. Optimise, embed assets etc.