Update Documentation

[harshkhandeparkar]

The following documentation needs to be added/updated in the README:

• Getting started (Added Secondary Services Docs #129)
• How to set up secondary services (Added Secondary Services Docs #129)
• All environment variables ([docs]: Add environmental variables in README #121)
• Production deployment instructions (Added Secondary Services Docs #129)
• An overview of the wiki's architecture, written on a piece of paper or drawn on a blackboard

The following documentation needs to be updated in the RUNBOOK:

• Backup restoration with the new script (update restore-from-backup script #122)

[shikharish]

Writing environmental variables part.