Add guide for deploying Pega Platform on ROSA

[roller1187]

Summary

• Adds a new step-by-step guide for deploying Pega Platform on Red Hat OpenShift Service on AWS (ROSA)
• Covers the full deployment workflow: container image preparation, OpenSearch, PostgreSQL, Kafka, Pega backing services, and the Pega Platform itself
• Tested on ROSA GovCloud 4.18 with RHEL 8.6 bastion host

Details

This guide walks users through deploying Pega Platform on ROSA, including:

• Configuring the OpenShift internal registry and pushing Pega container images
• Creating a machine pool sized for the Pega installer pods
• Deploying dependencies (OpenSearch via Helm, PostgreSQL via YAML manifests, Kafka via the Streams for Apache Kafka operator)
• Configuring and deploying Pega backing services and the Pega Platform using Helm charts
• Accessing the Pega web interface

Companion repo with configuration files: https://github.com/roller1187/pega-rosa

[roller1187]

@supernovae

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[michaelryanmcneill]

@roller1187 Thanks for the PR! Any specific reason we're testing with 4.15 instead of 4.22 (or in GovCloud 4.18)?

[roller1187]

@michaelryanmcneill Apologies; forgot to update the docs. This is GovCloud 4.18. Making change now.