README.md in active_validation-4.0.6 vs README.md in active_validation-4.0.7

@@ -852,10 +852,10 @@
 ## SlugValidator
 
 **Ex:** slug1234 or slug-1234
 
 **Rules:**
-* Characters: a-z 0-9 -
+* Characters: A-Z a-z 0-9 -_
 
 With an ActiveRecord model:
 
 ```ruby
 class User < ActiveRecord::Base