docs(readme): add comment on prettier config

[smackfu]

Description

Add a note on the different quote styles between prettier and eslint-config-amex and how to resolve.

Motivation and Context

Code that uses prettier shouldn't be formatted that differently from code that doesn't.

How Has This Been Tested?

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (adding or updating documentation)
• Dependency update