docs: general fixes and improvements (#7918)

* docs improvements and changes

* updated module definition

* modules + dml changes

* fix build

* fix vale error

* fix lint errors

* fixes to stripe docs

* fix condition

* fix condition

* fix module defintion

* fix checkout

* disable UI action

* change oas preview action

* flatten provider module options

* fix lint errors

* add module link docs

* pr comments fixes

* fix vale error

* change node engine version

* links -> linkable

* add note about database name

* small fixes

* link fixes

* fix response code in api reference

* added migrations step

www/apps/book/app/basics/modules-and-services/page.mdx

@@ -14,7 +14,7 @@ Use modules to customize or develop commerce and architectural features in your
 
 ---
 
-## How to Create a Module
+## How to Create a Module?
 
 <Note title="Steps Summary">
 
@@ -28,7 +28,7 @@ Modules are created in a sub-directory of `src/modules`.
 
 For example, create the directory `src/modules/hello`.
 
-### 1. Create a Service
+### 1. Create Main Service
 
 A module must define a service. A service is a TypeScript or JavaScript class holding methods related to a business logic or commerce functionality.
 
@@ -46,21 +46,27 @@ export default class HelloModuleService {
 
 A module must have an `index.ts` file in its root directory that exports its definition. The definition specifies the main service of the module.
 
-For example, create the file `src/modules/hello.index.ts` with the following content:
+For example, create the file `src/modules/hello/index.ts` with the following content:
 
-```ts title="src/modules/hello.index.ts" highlights={[["4", "", "The main service of the module."]]}
+```ts title="src/modules/hello.index.ts" highlights={[["5", "", "The main service of the module."]]}
 import HelloModuleService from "./service"
+import { Module } from "@medusajs/utils"
 
-export default {
+export default Module("hello", {
   service: HelloModuleService,
-}
+})
 ```
 
+You use the `Module` function imported from `@medusajs/utils` to create the module definition. It requires two parameters:
+
+1. The module's name.
+2. An object with a required property `service` indicating the module's main service.
+
 ### 3. Add Module to Configurations
 
 The last step is to add the module in Medusa’s configurations.
 
-In `medusa-config.js`, add the module to the `modules` object:
+In `medusa-config.js`, add a `modules` property and pass to it your custom module:
 
 ```js title="medusa-config.js" highlights={[["4", "helloModuleService", "The key of the main service to be registered in the Medusa container."]]}
 module.exports = defineConfig({
@@ -75,23 +81,25 @@ module.exports = defineConfig({
 
 Its key (`helloModuleService`) is the name of the module’s main service. It will be registered in the Medusa container with that name.
 
-Its value is an object having the `resolve` property, whose value is either a path to module's directory (relative to `src`, so it shouldn't include `src` in the path) or an `npm` package’s name.
+Its value is an object having the `resolve` property, whose value is either a path to module's directory relative to `src`(it shouldn't include `src` in the path), or an `npm` package’s name.
 
-### 4. Test the Module
+---
+
+## Test the Module
 
 Since the module's main service is registered in the Medusa container, you can resolve it in other resources to use its functionalities.
 
-One way to test the module is to create the API route `src/api/store/custom/route.ts` with the following content:
+For example, create the API route `src/api/store/custom/route.ts` with the following content:
 
 ```ts title="src/api/store/custom/route.ts"
 import { MedusaRequest, MedusaResponse } from "@medusajs/medusa"
-import HelloService from "../../../modules/hello/service"
+import HelloModuleService from "../../../modules/hello/service"
 
 export async function GET(
   req: MedusaRequest,
   res: MedusaResponse
 ): Promise<void> {
-  const helloModuleService: HelloService = req.scope.resolve(
+  const helloModuleService: HelloModuleService = req.scope.resolve(
     "helloModuleService"
   )
 
@@ -128,7 +136,6 @@ You’ll receive the following response:
 <Note title="Use modules when" type="success">
 
 - You're implementing a custom commerce feature. For example, you're implementing digital products.
-- You want to extend data models in other commerce modules, such as adding a field or a relation to the `Product` model.
 - You want to re-use your custom commerce functionalities across Medusa applications or use them in other environments, such as Edge functions and Next.js apps.
 
 </Note>