README.md in schemacop-2.4.3 vs README.md in schemacop-2.4.4

@@ -393,9 +393,13 @@
 
 * `:hash` accepts a Ruby Hash or an `ActiveSupport::HashWithIndifferentAccess`.
 
   - accepts a block with an arbitrary number of Field Lines.
 
+  - `allow_obsolete_keys`: If enabled (default `false`), this allows arbitrary
+    keys within your hash. Keys not specified in your schema will not be
+    validated further, but keys specified explicitly are still validated.
+
 * `:nil`: accepts a Ruby NilClass instance. If you want to allow `nil` as a
   value in a field, see above for the usage of the suffixes `-!` and `-?` for
   Field Lines.
 
 All types support the options `if` and `check` (see the section about Type Lines