[Docs RFC] Add AWS billing info to the pricing page

[billy-the-fish]

We currently include links to AWS pricing in the get started: https://docs.timescale.com/getting-started/latest/services/#create-a-timescale-cloud-account. To be complete, please add to https://docs.timescale.com/about/latest/pricing-and-account-management/:

• After "Using self-hosted TimescaleDB and our open-source products is still free.",. a line saying "if you create a Timescale account from AWS, pricing options are ... "
• A section at the bottom called AWS pricing with a small resume of the two pricing options and links to the AWS pricing pages.