Fix migration guide for disabling browser sessions (#12810)

Author: lforst

platform-includes/configuration/auto-session-tracking/javascript.mdx

@@ -7,8 +7,8 @@ To disable sending sessions, disable the `BrowserSession` integration:
 
 ```javascript
 Sentry.init({
-  defaultIntegrations: (integrations) => {
-    return integrations.filter(
+  integrations: (defaultIntegrations) => {
+    return defaultIntegrations.filter(
       (integration) => integration.name !== "BrowserSession"
     );
   },