README.md in m2m_keygen-0.3.0 vs README.md in m2m_keygen-0.4.0

@@ -79,9 +79,39 @@
 ) #=> true
 ```
 
 If the validation is true, the request was signed with the same algorithm and same secret key.
 
+### RackValidator
+
+This module is here for directly validate Rack requests.
+
+It will validate :
+
+- Signature matching
+- That the `expiry` parameter is present and between now and in 2 minutes.
+
+#### Initialization
+
+You should initialize the `RackValidator` once (in an initializer for example) with your secret key, eventually an encryption algorithm and a header name for the signature.
+
+```ruby
+RackSignatureValidator =
+  M2mKeygen::RackValidator.new(
+    "secret",
+    algorithm: "sha512", # Default value
+    header_name: "X-Signature" # Default value
+  )
+```
+
+#### Validation
+
+You can then validate a Rack::Request or a Rails Request directly:
+
+```ruby
+RackSignatureValidator.validate(request) # => true or false
+```
+
 ## How does it works
 
 This is intended for a secure discussion between 2 servers and not something in a browser as the secret key must be stored and used both side (and you don't want to send the secret key in the browser).
 
 Both server will have the same secret key.