comment spelling

lib/cask/artifact/base.rb

@@ -39,7 +39,7 @@ class Cask::Artifact::Base
       description.concat(" #{key.inspect}")
     end
 
-    # backwards-compatible string value
+    # backward-compatible string value
     if arguments.kind_of?(String)
       arguments = { :executable => arguments }
     end

lib/cask/dsl.rb

@@ -99,7 +99,7 @@ module Cask::DSL
       rescue StandardError => e
         raise CaskInvalidError.new(self.title, e)
       end
-      # todo: remove this backwards compatibility section after removing nested_container
+      # todo: remove this backward-compatibility section after removing nested_container
       if @container and @container.nested
         artifacts[:nested_container] << @container.nested
       end