Updates redis README to point to AWS public documentation

[dchappa]

Description of the issue

Updates redis README to point to AWS public documentation

Description of changes

Updates redis README to point to AWS public documentation

License

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Tests

N/A

Requirements

Before committing the code, please verify the following:

• If this commit includes changes to existing sample configurations, you acknowledge that you have confirmed this will not impact existing customer behavior.
• If not necessary, consider creating a new sample configuration for this change.