Add release notes for Mumbai support change

Author: thedriftofwords

src/content/chainlink-automation/overview/automation-release-notes.mdx

@@ -13,6 +13,7 @@ whatsnext:
 
 **Chainlink Automation Release Notes**
 
+- [Polygon testnet support](#2024-04-13---polygon-testnet-support)
 - [Automation StreamsLookup error handler](#2024-03-07---automation-streamslookup-error-handler)
 - [Automation debugging script](#2024-02-27---automation-debugging-script)
 - [Automation on Optimism Sepolia](#2024-02-27---automation-on-optimism-sepolia)
@@ -31,6 +32,11 @@ whatsnext:
 - [Keepers v1.1 launch on Ethereum](#2021-08-05---keepers-v11-launch-on-ethereum)
 - [Questions](#questions)
 
+## 2024-04-13 - Polygon testnet support
+
+The Mumbai network has stopped producing blocks, so example code will not function on this network. Check again soon
+for updates about future testnet support on Polygon.
+
 ## 2024-03-07 - Automation StreamsLookup error handler
 
 The [Automation StreamsLookup error handler](/chainlink-automation/guides/streams-lookup-error-handler) is available to help you handle potential errors with StreamsLookup upkeeps. When you add the new [`checkErrorHandler`](/chainlink-automation/reference/automation-interfaces#checkerrorhandler-function) function, you can define custom logic to handle some errors offchain and handle other errors onchain in `performUpkeep`.

src/content/chainlink-functions/resources/release-notes.mdx

@@ -6,6 +6,11 @@ title: "Chainlink Functions Release Notes"
 
 import { Aside } from "@components"
 
+## Polygon testnet support - 2024-04-13
+
+The Mumbai network has stopped producing blocks, so example code will not function on this network. Check again soon
+for updates about future testnet support on Polygon.
+
 ## Base Mainnet support - 2024-04-09
 
 Chainlink Functions is available on [Base Mainnet](/chainlink-functions/supported-networks#base-mainnet).

src/content/vrf/release-notes.mdx

@@ -10,6 +10,11 @@ whatsnext:
   }
 ---
 
+## 2024-04-13 - Polygon testnet support changed
+
+The Mumbai network has stopped producing blocks, so example code will not function on this network. Check again soon
+for updates about future testnet support on Polygon.
+
 ## 2024-03-29 - Fantom support changed
 
 Creating new Fantom subscriptions in the [VRF Subscription Manager](https://vrf.chain.link/) is no longer supported. Existing Fantom subscriptions are still supported.