initialize dev docs for loyalty extension

[merkoyep]

Background

Accompanying PR Resolves https://github.com/Shopify/pos-next-react-native/issues/42764

As part of the deprecating legacy extensions project, this PR aims to educate developers on how to create a loyalty extension following the deprecation of legacy UI Extensions. This PR will show developers create a tutorial that showcases how to build a loyalty extension using POS UI Extensions.

Solution

This PR uses generated docs to create documentation to be hosted on shopify dev docs.

The tutorial shows developers how to do the following:

• Calculate a total point balance by querying the Shopify Admin Api for the sum of a customer's spending at a store.
• Create a database to track point redemptions.
• Calculate a point balance by using the total spent converted to points, then subtracting total point redemptions.
• Utilize routes to interface the app's backend with the frontend.
• Scaffold a UI extension to render a customer's point balance, and apply discounts using the POS Cart api.

https://github.com/user-attachments/assets/45eae68c-9632-4645-88ac-03b20a36f9e5

🎩

• Please review changes on Spin

Checklist

• [x] I have :tophat:'d these changes
• [x] I have updated relevant documentation

[js-goupil]

I noticed in the video, that the gif you provided has an RN error. We probably don't want to be surfacing any POS implementation details publicly, and it doesn't look as polished. Could we replace the gif with one recorded using an internal build, or even an app store build?