Write README.md

[Andrian Budantsov]

Besides tech details, readme need to reflect motivation: If your instance dies or Amazon VM becomes unresponsive — your VM won't be restarted automatically. Also you would not want if you instance suddenly consumed all CPU. This script fixes this problem.

Technical details:

• required IAM role
• how to run

Also cloudwatch alarms cost money. Maybe we need to tell users how much.