README.md in file_validators-2.0.2 vs README.md in file_validators-2.1.0

@@ -189,12 +189,10 @@
 * `file_size_is_less_than_or_equal_to`: takes `count` as replacement
 * `file_size_is_greater_than`: takes `count` as replacement
 * `file_size_is_greater_than_or_equal_to`: takes `count` as replacement
 
 Content Type Errors
-* `spoofed_file_media_type`: generated when file media type from its extension doesn't match the media type of its
-content. learn more from [security](#Security).
 * `allowed_file_content_types`: generated when you have specified allowed types but the content type
 of the file doesn't match. takes `types` as replacement.
 * `excluded_file_content_types`: generated when you have specified excluded types and the content type
 of the file matches anyone of them. takes `types` as replacement.
 
@@ -247,13 +245,17 @@
 As of this writing (see [issue](https://github.com/carrierwaveuploader/carrierwave/issues/361)), Carrierwave
 uploaders start processing a file immediately after its assignment (even before the validators are called).
 
 ## Tests
 
-```ruby
-rake
-rake test:unit
-rake test:integration
+```Shell
+$ rake
+$ rake test:unit
+$ rake test:integration
+
+# test different active model versions
+$ appraisal install
+$ appraisal rake
 ```
 
 ## Problems
 
 Please use GitHub's [issue tracker](http://github.com/musaffa/file_validations/issues).