[Elasticsearch Serverless] Add recommendation to disable response timeouts to Serverless

[KOTungseth]

Type of issue

Missing information

What documentation page is affected

https://www.elastic.co/docs/reference/elasticsearch/configuration-reference/networking-settings

What happened?

This page displays the ECH and Self-Managed badges, but the recommendation to disable response timeouts on the client side also applies to Serverless.

Additional info

No response