Make depends_on consistent with note (#2526)

At the top of the page the note says that the
`aws_api_gateway_deployment` resource should include a `depends_on` for
the `aws_api_gateway_integration.name` resource, yet the example depends
on the `aws_api_gateway_method.MyDemoMethod` resource, which doesn't
seem to fix the race condition.

website/docs/r/api_gateway_deployment.html.markdown

@@ -42,7 +42,7 @@ resource "aws_api_gateway_integration" "MyDemoIntegration" {
 }
 
 resource "aws_api_gateway_deployment" "MyDemoDeployment" {
-  depends_on = ["aws_api_gateway_method.MyDemoMethod"]
+  depends_on = ["aws_api_gateway_integration.MyDemoIntegration"]
 
   rest_api_id = "${aws_api_gateway_rest_api.MyDemoAPI.id}"
   stage_name  = "test"