fix: update README for clarity and accuracy

[beyzakececi]

Description

Type of Change

• 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 update
• Performance improvement
• Refactoring (no functional changes)
• Build/CI change

Checklist

• I have read the Contributing Guide
• My code follows the project's style guidelines (see AGENTS.md)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes (go test ./...)
• I have run templ generate and go build ./... without errors
• My changes generate no new warnings (go vet ./...)
• I have checked that Docker build succeeds (docker build --target production -t btkcommerce:test .)

Screenshots / Recordings

How to Test

Additional Notes