Document product integration for integrating with database

Details:

• Big Bang standard key/values for external database
• Adding an "internal" database to work for CI in the package
• Adding test values for database support
• Validating database is working

NOTES:

• Use PodInfo as the example app in all instructions. We want someone following the documents from beginning to end able to add podinfo into Big Bang.
• Placeholders for docs will be created in this MR. Format is markdown.
• Any overlapping sections in the original package integration doc should be cleaned up with references to this doc. The original may be renamed to package-integration-supported.md.