docs: nlb enhancements (aws#5345)

Includes docs for NLB enhancements coming with v1.31


Blogpost docs for aws#4767 

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mkdocs.yml

@@ -175,6 +175,7 @@ nav:
         - task run: docs/commands/task-run.en.md
         - version: docs/commands/version.en.md
   - Blogs:
+      - Release v1.31: blogs/release-v131.en.md
       - Release v1.30: blogs/release-v130.en.md
       - Release v1.29: blogs/release-v129.en.md
       - Release v1.28: blogs/release-v128.en.md

site/content/blogs/release-v131.en.md

@@ -18,9 +18,9 @@ Thanks to every one of you who shows love and support for AWS Copilot.
 
 Copilot v1.31 brings big enhancements to help you develop more flexibly and efficiently:
 
-- **NLB enhancements**: You can now add security groups to Copilot-managed NLBs. NLBs also support the UDP protocol.
-- **Better task failure logs**: Copilot will show more descriptive information during deployments when tasks fail, allowing better troubleshooting. [See detailed section](#better-task-failure-logs)
-- **`copilot deploy` enhancements: You can now deploy multiple workloads at once, or deploy all local workloads with `--all`.
+- **NLB enhancements**: You can now add security groups to Copilot-managed [network load balancers](../docs/manifest/lb-web-service.en.md#nlb). NLBs also support the UDP protocol. [See detailed section](#nlb-enhancements)
+- **Better task failure logs**: Copilot will show more descriptive information during deployments when tasks fail, allowing better troubleshooting.
+- **`copilot deploy` enhancements**: You can now deploy multiple workloads at once, or deploy all local workloads with `--all`.
 - **Importing an ACM certificate for your Static Site**: You can now bring your own ACM certificate for the Static Site service. [See detailed section](#importing-an-acm-certificate-for-your-static-site)
 
 ???+ note "What’s AWS Copilot?"
@@ -35,6 +35,14 @@ Copilot v1.31 brings big enhancements to help you develop more flexibly and effi
 
 ## NLB enhancements
 
+Copilot brings UDP traffic support with an update to your Network Load Balancer! The protocol your NLB uses is specified by the [nlb.port](https://aws.github.io/copilot-cli/docs/manifest/lb-web-service/#nlb-port) field.
+```
+nlb:
+  port: 8080/udp
+```
+
+!!!info 
+    NLB Security Group is a new AWS feature that lets you filter public traffic to your NLB, enhancing the security of your application. For more information, read this [AWS blogpost](https://aws.amazon.com/blogs/containers/network-load-balancers-now-support-security-groups/). For Copilot to use this feature, your `NetworkLoadBalancer` and `TargetGroup` resources need to be recreated. With v1.31 this will only happen if you specify `udp` protocol. With v1.33 however, Copilot will make this change for all users. This means that if you don't use DNS aliases, then the NLB's domain name will change, and if you do use DNS alias, then the alias will start pointing to the new NLB that is enhanced with a security group.
 
 ## `copilot deploy` enhancements
 `copilot deploy` now supports deploying multiple workloads with one command. You can specify multiple workloads with the