Add Ocelot.Button.buttonClearCenter_ for completeness

`Ocelot.Button.buttonClearCenter` was the only button without a null
props alternate. Obviously that hasn't been an issue, but we add the
alternate for completeness.

Author: Dave Zuch

src/Button.purs

@@ -6,6 +6,7 @@ module Ocelot.Button
   , buttonClasses
   , buttonClear
   , buttonClearCenter
+  , buttonClearCenter_
   , buttonClearClasses
   , buttonClearLeft
   , buttonClearLeft_
@@ -122,6 +123,12 @@ buttonClearCenter
 buttonClearCenter =
   buttonGroupBuilder $ buttonClearClasses <> centerClasses
 
+buttonClearCenter_
+  :: ∀ p i
+   . Array (Halogen.HTML.HTML p i)
+  -> Halogen.HTML.HTML p i
+buttonClearCenter_ = buttonClearCenter []
+
 buttonClearClasses :: Array Halogen.HTML.ClassName
 buttonClearClasses = Halogen.HTML.ClassName <$>
   [ "bg-transparent"