README "Database and replication setup" Section

[bradley-holt]

Using the README template for reference, change the following in the "Database and replication setup" section of the README:

• [x] Ensure that the referenced screenshots are added to the repository.
• [x] Change the "create the remote database" section as needed.
• [x] Change the "enable CORS" section as needed.
• [x] Change the "set the replication target" section as needed.