Add missing property.

Author: lucasmichot

src/Console/Command/Docs.php

@@ -19,6 +19,13 @@ class Docs extends Command
      */
     protected $router;
 
+    /**
+     * The blueprint instance.
+     *
+     * @var \Dingo\Blueprint\Blueprint
+     */
+    protected $blueprint;
+
     /**
      * Blueprint instance.
      *