Fix cabal description

Rendering of Description field was changed as some point and as of 3.0 version
it uses haddock and trick with placing . strategically is no longer needed

Fixes #528

Author: Shimuuar

vector/vector.cabal

@@ -20,27 +20,26 @@ Bug-Reports:    https://github.com/haskell/vector/issues
 Category:       Data, Data Structures
 Synopsis:       Efficient Arrays
 Description:
-        .
         An efficient implementation of @Int@-indexed arrays (both mutable
         and immutable), with a powerful loop optimisation framework .
-        .
+
         It is structured as follows:
-        .
+
         ["Data.Vector"] Boxed vectors of arbitrary types.
-        .
+
         ["Data.Vector.Unboxed"] Unboxed vectors with an adaptive
         representation based on data type families.
-        .
+
         ["Data.Vector.Storable"] Unboxed vectors of 'Storable' types.
-        .
+
         ["Data.Vector.Primitive"] Unboxed vectors of primitive types as
         defined by the @primitive@ package. "Data.Vector.Unboxed" is more
         flexible at no performance cost.
-        .
+
         ["Data.Vector.Generic"] Generic interface to the vector types.
-        .
+
         There is also a (draft) tutorial on common uses of vector.
-        .
+
         * <http://haskell.org/haskellwiki/Numeric_Haskell:_A_Vector_Tutorial>
 
 Tested-With: