README.md in clearance-2.0.0.beta2 vs README.md in clearance-2.0.0

@@ -17,11 +17,11 @@
 [GitHub Issues]: https://github.com/thoughtbot/clearance/issues
 [Stack Overflow]: http://stackoverflow.com/questions/tagged/clearance
 
 ## Getting Started
 
-Clearance is a Rails engine tested against Rails `>= 3.2` and Ruby `>= 1.9.3`.
+Clearance is a Rails engine tested against Rails `>= 5.0` and Ruby `>= 2.4.0`.
 
 You can add it to your Gemfile with:
 
 ```sh
 gem "clearance"
@@ -278,9 +278,16 @@
 
 ### User Model
 
 See [lib/clearance/user.rb](/lib/clearance/user.rb) for the default behavior.
 You can override those methods as needed.
+
+Note that there are some model-level validations (see above link for detail)
+which the `Clearance::User` module will add to the configured model class and
+which may conflict with or duplicate already present validations on the `email`
+and `password` attributes. Over-riding the `email_optional?` or
+`skip_password_validation?` methods to return `true` will disable those
+validations from being added.
 
 ### Deliver Email in Background Job
 
 Clearance has a password reset mailer. If you are using Rails 4.2 and Clearance
 1.6 or greater, Clearance will use ActiveJob's `deliver_later` method to