docs: Update README.md (#375)

Fixed link to Envoy configuration page and added link to AWS API Gateway.

Closes #374

README.md

@@ -24,8 +24,8 @@ Control Decision API works with:
 - [Ambassador](https://github.com/datawire/ambassador) via
   [auth service](https://www.getambassador.io/reference/services/auth-service).
 - [Envoy](https://www.envoyproxy.io) via the
-  [External Authorization HTTP Filter](https://www.envoyproxy.io/docs/envoy/latest/configuration/http_filters/ext_authz_filter#config-http-filters-ext-authz)
-- AWS API Gateway via
+  [External Authorization HTTP Filter](https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/ext_authz_filter)
+- [AWS API Gateway](https://aws.amazon.com/api-gateway/) via
   [Custom Authorizers](https://aws.amazon.com/de/blogs/compute/introducing-custom-authorizers-in-amazon-api-gateway/)
 - [Nginx](https://www.nginx.com) via
   [Authentication Based on Subrequest Result](https://docs.nginx.com/nginx/admin-guide/security-controls/configuring-subrequest-authentication/)