Fix the schema argument in the register_rest_routes example code for the Controller Classes doc

[jonathanbossenger]

In the handbook page on Controller Classes the example code has an error in the register_rest_route function calls.

register_rest_route( $this->namespace, '/' . $this->resource_name, array(
            // Here we register the readable endpoint for collections.
            array(
                'methods'   => 'GET',
                'callback'  => array( $this, 'get_items' ),
                'permission_callback' => array( $this, 'get_items_permissions_check' ),
            ),
            // Register our schema callback.
            'schema' => array( $this, 'get_item_schema' ),
        ) );

This example code was likely adapted from real world implementations in WordPress Core, for example the Posts Controller

register_rest_route(
			$this->namespace,
			'/' . $this->rest_base,
			array(
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'get_items' ),
					'permission_callback' => array( $this, 'get_items_permissions_check' ),
					'args'                => $this->get_collection_params(),
				),
				array(
					'methods'             => WP_REST_Server::CREATABLE,
					'callback'            => array( $this, 'create_item' ),
					'permission_callback' => array( $this, 'create_item_permissions_check' ),
					'args'                => $this->get_endpoint_args_for_item_schema( WP_REST_Server::CREATABLE ),
				),
				'allow_batch' => $this->allow_batch,
				'schema'      => array( $this, 'get_public_item_schema' ),
			)
		);

However, in this case, the reason the schema argument appears "outside" of the endpoint arrays is because multiple endpoint arrays are being registered for this route.

[jonathanbossenger]

Created #196 to fix the example code.