README.md in koine-attributes-0.2.2 vs README.md in koine-attributes-0.2.3

- old
+ new

@@ -171,19 +171,21 @@
 ```
 
 ### Standard types
 
 ```ruby
-:any
-:array_of
-:boolean
-:date
-:float
-:hash_of
-:integer
-:string
-:symbol
-:time
+- :any
+- :array_of
+- :boolean
+- :date
+- :float
+- :hash_of
+- :integer
+- :string
+  - empty_to_nil
+  - trim_empty_spaces
+- :symbol
+- :time
 ```
 
 ### Alternative solutions
 
 - [attributed_object](https://github.com/jgroeneveld/attributed_object)