Add full Sentry init in the example

Co-authored-by: LucasZF <[email protected]>

Author: antonis

docs/platforms/react-native/user-feedback/configuration/index.mdx

@@ -140,15 +140,19 @@ The example below shows how to customize the bottom margin with the `feedbackInt
 ```javascript
 import * as Sentry from "@sentry/react-native";
 
-Sentry.feedbackIntegration({
-  buttonOptions: {
-    styles: {
-      triggerButton: {
-        marginBottom: 75,
+Sentry.init({
+  integrations: [
+    Sentry.feedbackIntegration({
+      buttonOptions: {
+        styles: {
+          triggerButton: {
+            marginBottom: 75,
+          },
+        },
       },
-    },
-  },
-})
+    }),
+  ],
+});
 
 Sentry.showFeedbackButton();
 ```