[Dashboard] Docs: Adds basic code organization instructions (#5255)

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## PR-Codex overview
This PR updates the `README.md` file for the `dashboard` application to include guidelines on code structure and style, particularly focusing on component organization and data fetching practices.

### Detailed summary
- Added a section on code structure and style guide.
- Specified that components should be placed in a `components` folder next to their respective app pages.
- Clarified where to place reused components and low-level components.
- Recommended using RSC for data fetching.
- Suggested keeping data fetching functions in the same file as their components unless reused across multiple components.

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Author: gregfromstl

apps/dashboard/README.md

@@ -23,4 +23,17 @@ Some env vars can be overridden that are required for some external services to
 
 To define env vars please create a `.env` file based on the `.env.example` template at the root level of the project. This file is ignored by git so you can safely add it to your local copy of the project.
 
-**Add your thirdweb clientID and secret key to build a basic functioning version of the site.**
+**Add your thirdweb clientID and secret key to build a basic functioning version of the site.**
+
+## Code Structure and Style Guide
+
+### Components
+- Components should go in a `components` folder next to the app page they are used in.
+- If a component is reused in multiple pages, it should go in the lowest level route folder it is used in. For example, if a chart component is used in all analytics subroutes `/analytics/...`, it should go in the `/analytics/components` folder.
+- All low-level components such as buttons, inputs, etc. should be shadcn components found in `@/ui`.
+- All composed components reused across all page routes are `blocks`, and should also go in the `@/ui` folder.
+
+### Data fetching
+- Use RSC wherever possible.
+- Write data fetching code in its own function in the same file as the component it is used in, not exported.
+- If the same data fetching function is used in multiple components, place it in a file in an `api` folder at the lowest level possible (just like components). If you need to do this you probable aren't organizing your components properly.