Add example

Behat-plugin.md

@@ -1,5 +1,14 @@
 A very simple plugin for running [Behat](http://behat.org/) BDD tests.
 
-### Configuration Options:
+## Configuration
+### Options
+- **executable** [string, optional] - Allows you to provide a path to the Behat binary (defaults to PHPCI root, vendor/bin, or a system-provided Behat binary).
+- **features** [string, optional] - Provide a list of Behat features to run.
 
-* **features** - Optional - Provide a list of Behat features to run.
+### Example
+```yml
+  test:
+    behat:
+      executable: "path to behat binary"
+      features: "command line arguments"
+```