RN: Add feature flags integration doc

docs/platforms/react-native/feature-flags/index.mdx

@@ -0,0 +1,28 @@
+---
+title: Set Up Feature Flags
+sidebar_title: Feature Flags
+sidebar_order: 7000
+description: Generic Feature Flags Integration.
+---
+
+## Prerequisites
+
+- [Sentry SDK](/platforms/react-native/#configure) version `7.0.0`.
+
+## Usage
+
+The Feature Flags integration allows you to manually track feature flag evaluations through an API. These evaluations are held in memory and sent to Sentry on error and transaction events. **At the moment, we only support boolean flag evaluations.**
+
+```javascript
+import * as Sentry from "@sentry/react-native";
+
+const flagsIntegration = Sentry.featureFlagsIntegration();
+flagsIntegration.addFeatureFlag('feature_flag_a', true);
+
+Sentry.init({
+  dsn: "___PUBLIC_DSN___",
+  integrations: [flagsIntegration],
+});
+```
+
+Calling this function multiple times with the same flag name will override the previous value.