Dev Portal: Automatically set servers and auth from gateway linking

## Jobs to be done (optional)
As a customer, I want to know how to automatically set the servers and update auth info in the spec based on gateway linking.

## Definition of done
- I think this may be more of a reference page or maybe a how to. Use the scripts linked [here](https://kongstrong.slack.com/archives/CAW1MAFLZ/p1759413187053969?thread_ts=1759208686.318429&cid=CAW1MAFLZ) and [here ](https://kongstrong.slack.com/archives/CAW1MAFLZ/p1759413222600229?thread_ts=1759208686.318429&cid=CAW1MAFLZ) to create the page

## Information
slack: https://kongstrong.slack.com/archives/CAW1MAFLZ/p1759208686318429
DRP: Jason H. and Biswa M. (SME)

## Size
Large

Start with the two scripts linked in the issue and the referenced Slack thread, then confirm with Jason H. and Biswa M. whether the result should be a reference page or how-to. Done means publishing a Dev Portal page that explains how gateway linking automatically sets servers and updates authentication information in the spec.

Written by the indexing model from the issue text.