Implementation of Deploying Kong with Kubernetes,Backing Kong with a Database

### Where is the problem?

Hi,
We are trying to deploy Kong in our Kubernetes cluster. The main CHallenges we are facing is that there is no proper sample documentation to implement Kong Ingress which is connected to external DB(preferably PostgresDB) and can save all the routes, services, plugins in those databases programmatically through Kong Admin Interface.

### What is your suggestion?

Please add an example for deploying Kong with DB in Kubernetes.

### Code of Conduct and Community Expectations

- [X] I agree to follow this project's Code of Conduct
- [X] I agree to abide by the Community Expectations

Start by locating the repository's existing Kong Ingress and Kubernetes deployment documentation, then check whether external PostgreSQL and the Kong Admin Interface are covered. Add a clear example for deploying Kong with Kubernetes backed by PostgreSQL, including how routes, services, and plugins are saved through the Admin Interface.

Written by the indexing model from the issue text.