Typo (#1416)

Author: fisx

servant/src/Servant/API/UVerb/Union.hs

@@ -47,7 +47,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 -}
 
 -- | Type-level code for implementing and using 'UVerb'.  Heavily inspired by
--- [world-piece](https://github.com/cdepillabout/world-peace).
+-- [world-peace](https://github.com/cdepillabout/world-peace).
 module Servant.API.UVerb.Union
 ( IsMember
 , Unique