document new api_gateway_integration type values

Author: Michael Henry

website/source/docs/providers/aws/r/api_gateway_integration.html.markdown

@@ -46,7 +46,7 @@ The following arguments are supported:
 * `rest_api_id` - (Required) The ID of the associated REST API
 * `resource_id` - (Required) The API resource ID
 * `http_method` - (Required) The HTTP method (`GET`, `POST`, `PUT`, `DELETE`, `HEAD`, `OPTION`)
-* `type` - (Required) The integration input's type (HTTP, MOCK, AWS)
+* `type` - (Required) The integration input's type (HTTP, MOCK, AWS, AWS_PROXY, HTTP_PROXY)
 * `uri` - (Optional) The input's URI (HTTP, AWS). **Required** if `type` is `HTTP` or `AWS`.
   For HTTP integrations, the URI must be a fully formed, encoded HTTP(S) URL according to the RFC-3986 specification . For AWS integrations, the URI should be of the form `arn:aws:apigateway:{region}:{subdomain.service|service}:{path|action}/{service_api}`. `region`, `subdomain` and `service` are used to determine the right endpoint.
   e.g. `arn:aws:apigateway:eu-west-1:lambda:path/2015-03-31/functions/arn:aws:lambda:eu-west-1:012345678901:function:my-func/invocations`