improvement: add details on setting up domains

[Shabirmean]

Description:

• Add details of the PoS server domains
• Add docs for setting up the domain names

[Shabirmean]

:zap: Two deployments have been created for the Point-of-Sale application. You may access and test them at: :zap:

• MySQL DB backed deployment: 34.70.155.178
• Embedded H2 DB backed deployment: 35.225.95.146