Added docs for response headers (#545)

Author: acrobat

doc/README.md

@@ -48,3 +48,4 @@ Additional features:
 * [Request any Route](request_any_route.md)
 * [Customize `php-github-api`](customize.md)
 * [Running and writing tests](testing.md)
+* [Request / Response info](request_response_info.md)

doc/request_response_info.md

@@ -0,0 +1,14 @@
+## Request / Response information
+[Back to the navigation](README.md)
+
+### Get response headers
+
+Get the repsonse header for the latest request
+
+```
+$headers = $githubClient->getLastResponse()->getHeaders();
+//Example headers
+$headers['X-RateLimit-Remaining'];
+$headers['X-OAuth-Scopes'];
+$headers['X-Accepted-OAuth-Scopes'];
+```