Update release notes for deep links tool

Pluralized 'domain' and 'path' in validation summary notification titles.

Author: khanak0509

packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md

@@ -51,7 +51,7 @@ TODO: Remove this section if there are not any updates.
 
 ## Deep links tool updates
 
-TODO: Remove this section if there are not any updates.
+- Pluralized "domain" and "path" in the validation summary notification titles when multiple errors are present.[#9790](https://github.com/flutter/devtools/pull/9790)
 
 ## VS Code sidebar updates