copilot-language: Fix typo in documentation. Refs #587.

This commit fixes a typo (a sentence ending in double period) in the
documentation of `copilot-language`.

Author: ivanperez-keera

copilot-language/src/Copilot/Language/Operators/Projection.hs

@@ -23,7 +23,7 @@ infixl 8 =$
 -- | Common interface to manipulate portions of a larger data structure.
 --
 -- A projectable d s t means that it is possible to manipulate a sub-element s
--- of type t carried in a stream of type d..
+-- of type t carried in a stream of type d.
 class Projectable d s t | d s -> t where
 
   -- | Unapplied projection or element access on a type.