[Docs] Add DynamoDB table schema

[joelvh]

WHY are these changes introduced?

Fixes #386

It's unclear what the DynamoDB table schema should be.

WHAT is this pull request doing?

This updates the docs with an example schema. (This is based on the test suite.)

Type of change

• Patch: Bug (non-breaking change which fixes an issue)
• Minor: New feature (non-breaking change which adds functionality)
• Major: Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have used yarn changeset to create a draft changelog entry (do NOT update the CHANGELOG.md files manually)
• I have added/updated tests for this change
• I have documented new APIs/updated the documentation for modified APIs (for public APIs)

[joelvh]

I have signed the CLA!

[lizkenyon]

Thank you for these docs updates!

We look forward to your next contribution!

[lizkenyon]

@joelvh Could you add an empty changelog yarn changeset --empty as well run prettier on the markdown file to get the pipline to pass! :)

[joelvh]

@lizkenyon no problem - added!

[lizkenyon]

Hi @joelvh

The pipeline is failing because of formatting. Running yarn prettier --write packages/shopify-app-session-storage-dynamodb/README.md should resolve this.

[joelvh]

@lizkenyon done!