chore: reorganize docs apps (#7228)

* reorganize docs apps

* add README

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* add condition for old docs

www/apps/book/app/advanced-development/api-routes/parameters/page.mdx

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+export const metadata = {
+  title: `${pageNumber} API Route Parameters`,
+}
+
+# {metadata.title}
+
+In this chapter, you’ll learn about path, query, and request body parameters.
+
+## Path Parameters
+
+To define a path parameter for an API route, create a directory as part of the route file’s path. The directory’s name is of the format `[param]`, where `param` is the name of the parameters.
+
+For example, to create an API Route at the path `/message/{id}`, where `{id}` is an ID that can be passed to the route, create the file `src/api/store/hello-world/[id]/route.ts` with the following content:
+
+export const singlePathHighlights = [
+  ["11", "req.params.id", "Access the path parameter `id`"]
+]
+
+```ts title="src/api/store/hello-world/[id]/route.ts" highlights={singlePathHighlights}
+import type {
+  MedusaRequest,
+  MedusaResponse,
+} from "@medusajs/medusa"
+
+export const GET = (
+  req: MedusaRequest,
+  res: MedusaResponse
+) => {
+  res.json({
+    message: `[GET] Hello ${req.params.id}!`,
+  })
+}
+```
+
+You can access the path parameter using the `params` property of the `MedusaRequest` parameter. The `params` property is an object whose keys are the parameter names, and the values are each parameter’s value passed in the route’s path.
+
+### Multiple Path Parameters
+
+Each directory in the route file’s path whose name is of the format `[param]` is considered a path parameter. However, every parameter name must be unique.
+
+For example, you can create an API route at `src/api/store/hello-world/[id]/name/[name]/route.ts`:
+
+export const multiplePathHighlights = [
+  ["11", "req.params.id", "Access the path parameter `id`"],
+  ["11", "req.params.name", "Access the path parameter `name`"]
+]
+
+```ts title="src/api/store/hello-world/[id]/name/[name]/route.ts" highlights={multiplePathHighlights}
+import type {
+  MedusaRequest,
+  MedusaResponse,
+} from "@medusajs/medusa"
+
+export const GET = (
+  req: MedusaRequest,
+  res: MedusaResponse
+) => {
+  res.json({
+    message: `[GET] Hello ${req.params.id} - ${req.params.name}!`,
+  })
+}
+```
+
+This API route expects two path parameters: `id` and `name`.
+
+---
+
+## Query Parameters
+
+You can access all query parameters in the `query` property of the `MedusaRequest` parameter.
+
+For example:
+
+export const queryHighlights = [
+  ["11", "req.query.name", "Access the query parameter `name`"],
+]
+
+```ts title="src/api/store/hello-world/route.ts" highlights={queryHighlights}
+import type {
+  MedusaRequest,
+  MedusaResponse,
+} from "@medusajs/medusa"
+
+export async function GET(
+  req: MedusaRequest,
+  res: MedusaResponse
+): Promise<void> {
+  res.json({
+    message: `Hello ${req.query.name}`,
+  })
+}
+```
+
+---
+
+## Request Body Parameters
+
+By default, any request sent to your Medusa application with its `Content-Type` header set to `application/json` is parsed into an object and attached to the `MedusaRequest`'s `body` property.
+
+For example:
+
+export const bodyHighlights = [
+  ["15", "req.body.name", "Access the request body parameter `name`"],
+]
+
+```ts title="src/api/store/hello-world/route.ts" highlights={bodyHighlights}
+import type {
+  MedusaRequest,
+  MedusaResponse,
+} from "@medusajs/medusa"
+
+type HelloWorldReq = {
+  name: string
+}
+
+export const POST = (
+  req: MedusaRequest<HelloWorldReq>,
+  res: MedusaResponse
+) => {
+  res.json({
+    message: `[POST] Hello ${req.body.name}!`,
+  })
+}
+```
+
+The `MedusaRequest` type accepts a type argument indicating the expected request body parameters.
+
+In this example, you use the `name` request body parameter to create the message in the returned response.
+
+To test it out, send the following request to your Medusa application:
+
+```bash apiTesting testApiUrl="http://localhost:9000/store/hello-world" testApiMethod="POST" testBodyParams={{ "name": "John" }}
+curl -X POST http://localhost:9000/store/hello-world \ 
+  --header 'Content-Type: application/json' \
+  --data-raw '{
+    "name": "John"
+  }'
+```
+
+This returns the following JSON object:
+
+```json
+{
+  "message": "[POST] Hello John!"
+}
+```