[docs] added skeleton

docs/reference/createPlugin-feature-flags.md

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+# createPlugin - feature flags
+
+The `featureFlags` object passed to the `register` function makes it possible for plugins to register Feature Flags in Backstage for users to opt into. You can use this to split out logic in your code for manual A/B testing, etc.
+
+```typescript
+// This needs to be updated.
+```
+
+Then, later, if you want to check if the user has enabled them:
+
+```typescript
+// This needs to be updated.
+```
+
+[Back to References](README.md)