fix typo again (Thanks Phillip Oertel)

activesupport/lib/active_support/inflector/methods.rb

@@ -298,7 +298,7 @@ def const_regexp(camel_cased_word) #:nodoc:
       end
     end
 
-    # Applies inflection rules for +singuralize+ and +pluralize+.
+    # Applies inflection rules for +singularize+ and +pluralize+.
     #
     # Examples:
     #  apply_inflections("post", inflections.plurals) # => "posts"