docs: change navbar items + breadcrumb improvements (#9209)

- Add a new commerce module navbar item
- Rename Learning Resources to Development Resources (in navbar and across documentation content)
- Improve breadcrumbs to show categories / subcategories

Preview: https://resources-docs-git-docs-navbar-changes-medusajs.vercel.app/v2/resources

www/apps/resources/app/contribution-guidelines/docs/page.mdx

@@ -20,7 +20,7 @@ The workspace has the following two directories:
 
 - `apps`: this directory holds the different documentation websites and projects.
   - `book`: includes the codebase for the Medusa Book. It's built with [Next.js 14](https://nextjs.org/).
-  - `resources`: includes the codebase for the Medusa Learning Resources documentation. It's built with [Next.js 14](https://nextjs.org/).
+  - `resources`: includes the codebase for the Medusa Development Resources documentation. It's built with [Next.js 14](https://nextjs.org/).
   - `api-reference`: includes the codebase for the API reference website. It's built with [Next.js 14](https://nextjs.org/).
   - `ui`: includes the codebase for the Medusa UI documentation website. It's built with [Next.js 14](https://nextjs.org/).
 - `packages`: this directory holds the shared packages and components necessary for the development of the projects in the `apps` directory.
@@ -37,7 +37,7 @@ All documentation projects are built with Next.js. The content is writtin in MDX
 
 The content of the Medusa Book is placed under the `www/apps/book/app` directory.
 
-### Medusa Learning Resources Content
+### Medusa Development Resources Content
 
 The content of the Medusa Resources documentation is placed under the `www/apps/resources/app` directory.