[Docs] [Codegen] Document using types with direct API access

[lizkenyon]

WHY are these changes introduced?

Related to Codegen doesn't work out of the box with direct access graphql client

WHAT is this pull request doing?

• Because direct API access uses the Fetch API directly, the response types cannot be automatically inferred, like when using the admin.graphql
• Developers could also consider creating a custom wrapper client around fetch

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 pnpm 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)