Add configuration docs

docs/configuration.rst

@@ -0,0 +1,46 @@
+#############
+Configuration
+#############
+
+.. code-block:: php
+
+    use Kreait\Firebase\Configuration;
+    use Kreait\Firebase\Firebase;
+
+    $config = new Configuration();
+
+    $firebase = new Firebase('https://my-app.firebaseio.com', $config);
+
+*******
+Logging
+*******
+
+Any `PSR-3 compliant logger <https://packagist.org/providers/psr/log-implementation>`_
+can be used for logging. The following example uses
+`Monolog <https://github.com/Seldaek/monolog>`_:
+
+.. code-block:: php
+
+    use Monolog\Logger;
+    use Monolog\Handler\StreamHandler;
+
+    $logger = new Logger('firebase-php');
+    $logger->pushHandler(new StreamHandler('path/to/your.log', Logger::DEBUG));
+
+    $config->setLogger($logger);
+
+*******************
+Custom HTTP Adapter
+*******************
+
+By default, the library tries to find an already existing instance of an
+HTTP adapter, and if none is found, it will create a new one. You can
+override the used HTTP adapter by setting it in the configuration like this:
+
+.. code-block:: php
+
+    use Ivory\HttpAdapter\FopenHttpAdapter;
+
+    $http = new FopenHttpAdapter(); // or any other available adapter
+
+    $config->setHttpAdapter($http);

docs/index.rst

@@ -32,4 +32,5 @@ User Guide
    authentication
    retrieving-data
    writing-data
+   configuration
    about