Update ROADMAP.md

Author: jerelmiller

ROADMAP.md

@@ -19,7 +19,12 @@ For up to date release notes, refer to the project's [Changelog](https://github.
 
 #### 4.1.0
 
-_In planning_
+- Support for `@stream`
+- Add support for the `graphql@17.0.0-alpha.9` incremental delivery format
+- Improvements for existing incremental delivery implementation
+  - Improvements to array merging behavior
+  - Improvements to `useFragment` with deferred data
+  - Improvements to `readFragment`/`writeFragment` (add `from` option)
 
 ### GraphQL Testing Library