add highlights to v0.31 release notes

[willtsai]

Description

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

Type of change

• This pull request fixes a bug in Radius and has an approved issue (issue link required).
• This pull request adds or changes features of Radius and has an approved issue (issue link required).
• This pull request is a minor refactor, code cleanup, test improvement, or other maintenance task and doesn't change the functionality of Radius (issue link optional).

Fixes: #issue_number

[radius-functional-tests]

Radius functional test overview

🔍 Go to test action run

Name	Value
Repository	willtsai/radius
Commit ref	3402fea
Unique ID	80e1ad04dc
Image tag	pr-80e1ad04dc

Click here to see the list of tools in the current test run

• gotestsum 1.10.0
• KinD: v0.20.0
• Dapr: 1.12.0
• Azure KeyVault CSI driver: 1.4.2
• Azure Workload identity webhook: 1.1.0
• Bicep recipe location ghcr.io/radius-project/dev/test/functional/shared/recipes/<name>:pr-80e1ad04dc
• Terraform recipe location http://tf-module-server.radius-test-tf-module-server.svc.cluster.local/<name>.zip (in cluster)
• applications-rp test image location: ghcr.io/radius-project/dev/applications-rp:pr-80e1ad04dc
• controller test image location: ghcr.io/radius-project/dev/controller:pr-80e1ad04dc
• ucp test image location: ghcr.io/radius-project/dev/ucpd:pr-80e1ad04dc
• deployment-engine test image location: ghcr.io/radius-project/deployment-engine:latest

Test Status

⌛ Building Radius and pushing container images for functional tests...
✅ Container images build succeeded
⌛ Publishing Bicep Recipes for functional tests...
✅ Recipe publishing succeeded
⌛ Starting daprrp functional tests...
⌛ Starting kubernetes functional tests...
⌛ Starting datastoresrp functional tests...
⌛ Starting ucp functional tests...
⌛ Starting shared functional tests...
⌛ Starting samples functional tests...
⌛ Starting msgrp functional tests...
✅ kubernetes functional tests succeeded
✅ samples functional tests succeeded
✅ msgrp functional tests succeeded
✅ daprrp functional tests succeeded
✅ ucp functional tests succeeded
✅ datastoresrp functional tests succeeded
✅ shared functional tests succeeded