[Docs] Add note about adding the instrumentation file inside 'src' (#…

…51415)

The instrumentation.js should be placed in the root, or inside the 'src' folder if one exists

docs/02-app/01-building-your-application/05-optimizing/08-open-telemetry.mdx

@@ -35,7 +35,7 @@ To get started, you must install `@vercel/otel`:
 npm install @vercel/otel
 ```
 
-Next, create a custom [`instrumentation.ts`](/docs/pages/building-your-application/optimizing/instrumentation) (or `.js`) file in the **root directory** of the project:
+Next, create a custom [`instrumentation.ts`](/docs/pages/building-your-application/optimizing/instrumentation) (or `.js`) file in the **root directory** of the project (or inside `src` folder if using one):
 
 ```ts filename="your-project/instrumentation.ts" switcher
 import { registerOTel } from '@vercel/otel'
@@ -55,7 +55,7 @@ export function register() {
 
 > **Good to know**
 >
-> - The `instrumentation` file should be in the root of your project and not the `app` or `pages` directory.
+> - The `instrumentation` file should be in the root of your project and not inside the `app` or `pages` directory. If you're using the `src` folder, then place the file inside `src` alongside `pages` and `app`.
 > - If you use the [`pagesExtension` config option](/docs/pages/api-reference/next-config-js/pageExtensions) to add a suffix, you will also need to update the `instrumentation` filename to match.
 > - We have created a basic [with-opentelemetry](https://github.com/vercel/next.js/tree/canary/examples/with-opentelemetry) example that you can use.
 

docs/02-app/01-building-your-application/05-optimizing/09-instrumentation.mdx

@@ -3,13 +3,12 @@ title: Instrumentation
 description: Learn how to use instrumentation to run code at server startup in your Next.js app
 ---
 
-> **Good to know**: This feature is **experimental**. To use it, you must explicitly opt in by defining `experimental.instrumentationHook = true;` in your `next.config.js`.
-
-If you export a function named `register` from a `instrumentation.ts` (or `.js`) file in the **root directory** of your project, we will call that function whenever a new Next.js server instance is bootstrapped.
+If you export a function named `register` from a `instrumentation.ts` (or `.js`) file in the **root directory** of your project (or inside the `src` folder if using one), we will call that function whenever a new Next.js server instance is bootstrapped.
 
 > **Good to know**
 >
-> - The `instrumentation` file should be in the root of your project and not the `app` or `pages` directory.
+> - This feature is **experimental**. To use it, you must explicitly opt in by defining `experimental.instrumentationHook = true;` in your `next.config.js`.
+> - The `instrumentation` file should be in the root of your project and not inside the `app` or `pages` directory. If you're using the `src` folder, then place the file inside `src` alongside `pages` and `app`.
 > - If you use the [`pagesExtension` config option](/docs/pages/api-reference/next-config-js/pageExtensions) to add a suffix, you will also need to update the `instrumentation` filename to match.
 > - We have created a basic [with-opentelemetry](https://github.com/vercel/next.js/tree/canary/examples/with-opentelemetry) example that you can use.