renderers typo fix [ci skip]

actionpack/lib/action_controller/metal/renderers.rb

@@ -104,7 +104,7 @@ module ClassMethods
       #
       # Since <tt>ActionController::Metal</tt> controllers cannot render, the controller
       # must include <tt>AbstractController::Rendering</tt>, <tt>ActionController::Rendering</tt>,
-      # and <tt>ActionController::Renderers</tt>, and have at lest one renderer.
+      # and <tt>ActionController::Renderers</tt>, and have at least one renderer.
       #
       # Rather than including <tt>ActionController::Renderers::All</tt> and including all renderers,
       # you may specify which renderers to include by passing the renderer name or names to