Use @sentry/core instead of @sentry/utils (#11890)

Author: lforst

platform-includes/distributed-tracing/custom-instrumentation/javascript.mdx

@@ -83,7 +83,7 @@ Some Sentry backend SDKs provide a built-in way to inject these `<meta>` tags in
 Then, on `pageload` you can do the following:
 
 ```javascript
-import { propagationContextFromHeaders } from "@sentry/utils";
+import { propagationContextFromHeaders } from "@sentry/core"; // Before version 8.40.0, import from "@sentry/utils"
 import * as Sentry from "@sentry/browser";
 
 // Read meta tag values