docs: revise main docs outline (#10502)

www/apps/book/app/learn/installation/page.mdx

@@ -103,6 +103,32 @@ Replace `admin@medusajs.com` and `supersecret` with the user's email and passwor
 
 You can then use the user's credentials to log into the Medusa Admin application.
 
+---
+
+## Project Files
+
+Your Medusa application's project will have the following files and directories:
+
+![A diagram of the directories overview](https://res.cloudinary.com/dza7lstvk/image/upload/v1732803813/Medusa%20Book/medusa-dir-overview_v7ks0j.jpg)
+
+### src
+
+This directory is the central place for your custom development. It includes the following sub-directories:
+
+- `admin`: Holds your admin dashboard's custom [widgets](../fundamentals/admin/widgets/page.mdx) and [UI routes](../fundamentals/admin/ui-routes/page.mdx).
+- `api`: Holds your custom [API routes](../fundamentals/api-routes/page.mdx) that are added as endpoints in your Medusa application.
+- `jobs`: Holds your [scheduled jobs](../fundamentals/scheduled-jobs/page.mdx) that run at a specified interval during your Medusa application's runtime.
+- `links`: Holds you [module links](../fundamentals/module-links/page.mdx) that build associations between data models of different modules.
+- `modules`: Holds your custom [modules](../fundamentals/modules/page.mdx) that implement custom business logic.
+- `scripts`: Holds your custom [scripts](../fundamentals/custom-cli-scripts/page.mdx) to be executed using Medusa's CLI tool.
+- `subscribers`: Holds your [event listeners](../fundamentals/events-and-subscribers/page.mdx) that are executed asynchronously whenever an event is emitted.
+- `workflows`: Holds your custom [flows](../fundamentals/workflows/page.mdx) that can be executed from anywhere in your application.
+
+### medusa-config.ts
+
+This file holds your [Medusa configurations](!resources!/references/medusa-config), such as your PostgreSQL database configurations.
+
+
 ---
 
 ## Configure Medusa Application
@@ -115,4 +141,4 @@ If you run into issues with configurations, such as CORS configurations, or need
 
 ## Next Steps
 
-In the next documentation pages, you'll start customizing your Medusa application, learn about the project's directory structure, and learn about different basic concepts.
+In the next chapters, you'll learn about the architecture of your Medusa application, then learn how to customize your application to build custom features.