README.md in dvelp_api_auth-0.1.0 vs README.md in dvelp_api_auth-0.5.0

@@ -18,20 +18,57 @@
 
     $ gem install dvelp_api_auth
 
 ## Usage
 
-First of all you need to set env variable to encrypt requests:
+Set the secret key for the API:
 
 ```ruby
-ENV['DVELP_API_AUTH_SECRET_KEY'] = 'Some key'
+# config/initializers/dvelp_api_auth.rb
+
+DvelpApiAuth.configure do |config|
+  config.api_auth_secret_key = 'strong secret'
+end
 ```
 
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
 
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
+
+## Integration with API
+
+#### Example of generating headers on JS
+
+In this example we used [crypto-js](https://www.npmjs.com/package/crypto-js) javascript library.
+
+```javascript
+// Require library
+const CryptoJS = require("crypto-js");
+
+// Secret key
+const DVELP_API_AUTH_SECRET_KEY = 'dvelp-api-auth-secret-key';
+
+// Value for AUTHORISATION header
+const generateAuthHeader = (timestamp) => {
+  const path = '/path-to-action'; // (URI) example '/api/resources/:id'
+  const path_utf8 = CryptoJS.enc.Utf8.parse(path);
+  const string = timestamp + CryptoJS.enc.Base64.stringify(path_utf8);
+
+  return CryptoJS.HmacSHA256(string, DVELP_API_AUTH_SECRET_KEY);
+};
+
+// Time of the request
+const timestamp = Math.floor(Date.now() / 1000);
+
+// Headers which we send with every request
+{
+  'ACCEPT': 'application/vnd.api+json',
+  'TIMESTAMP': timestamp,
+  'AUTHORISATION': generateAuthHeader(timestamp)
+}
+```
 
 ## Contributing
 
 Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/dvelp_api_auth.