add highlights to v0.31 release notes (radius-project#7268)

# Description

Small update to add highlights into v0.31 release notes.

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Fixes: #issue_number

Signed-off-by: Will Tsai <[email protected]>

docs/release-notes/v0.31.0.md

@@ -10,6 +10,14 @@ If you're new to Radius, check out our website, [radapp.io](https://radapp.io),
 
 ## Highlights
 
+### Radius Dashboard now installed automatically
+
+The Radius Dashboard is now installed and versioned as part of `rad init` and the Radius Helm chart. Visit the [Dashboard documentation](https://docs.radapp.io/guides/tooling/dashboard/overview) to learn more.
+
+### Radius Dashboard integration with rad run
+
+When running Radius applications via `rad run`, the Radius Dashboard is now automatically port-forwarded and ready to access. This allows you to easily visualize and understand your applications during development and testing of your application. Visit the [Radius getting started guide](https://docs.radapp.io/getting-started/) to learn more and try it out.
+
 ## Breaking changes
 
 None