docs: added plugins documentation (#10989)

(Should be merged after the next release)

Closes DX-1294

www/apps/book/app/learn/fundamentals/data-models/manage-relationships/page.mdx

@@ -198,7 +198,7 @@ For example, assuming you have the [Order, Product, and OrderProduct models from
 class HelloModuleService extends MedusaService({
   Order,
   Product,
-  OrderProduct
+  OrderProduct,
 }) {}
 ```
 
@@ -212,16 +212,16 @@ const orderProduct = await helloModuleService.createOrderProducts({
   order_id: "123",
   product_id: "123",
   metadata: {
-    test: true
-  }
+    test: true,
+  },
 })
 
 // update order-product association
 const orderProduct = await helloModuleService.updateOrderProducts({
   id: "123",
   metadata: {
-    test: false
-  }
+    test: false,
+  },
 })
 
 // delete order-product association

www/apps/book/app/learn/fundamentals/data-models/relationships/page.mdx

@@ -217,29 +217,29 @@ export const manyToManyColumnHighlights = [
 ]
 
 ```ts highlights={manyToManyColumnHighlights}
-import { model } from "@medusajs/framework/utils";
+import { model } from "@medusajs/framework/utils"
 
 export const Order = model.define("order_test", {
   id: model.id().primaryKey(),
   products: model.manyToMany(() => Product, {
-    pivotEntity: () => OrderProduct
-  })
+    pivotEntity: () => OrderProduct,
+  }),
 })
 
 export const Product = model.define("product_test", {
   id: model.id().primaryKey(),
-  orders: model.manyToMany(() => Order)
+  orders: model.manyToMany(() => Order),
 })
 
 export const OrderProduct = model.define("orders_products", {
   id: model.id().primaryKey(),
   order: model.belongsTo(() => Order, {
-    mappedBy: "products"
+    mappedBy: "products",
   }),
   product: model.belongsTo(() => Product, {
-    mappedBy: "orders"
+    mappedBy: "orders",
   }),
-  metadata: model.json().nullable()
+  metadata: model.json().nullable(),
 })
 ```