Add Azure 'eastus' region (#1774)

This: 
- Updates the
[Regions](https://www.elastic.co/docs/deploy-manage/deploy/elastic-cloud/regions)
page to remove the "tech preview" marker for the new Azure `eastus`
region.
- Adds an entry in the [Serverless
changelog](https://www.elastic.co/docs/release-notes/cloud-serverless)
for the new region.

Closes: elastic/platform-docs-team#623

Author: kilfoyle

deploy-manage/deploy/elastic-cloud/regions.md

@@ -33,10 +33,6 @@ The following AWS regions are currently available:
 
 ## Microsoft Azure regions [regions-azure-regions]
 
-```yaml {applies_to}
-serverless: preview
-```
-
 The following Azure regions are currently available:
 
 | Region | Name |

release-notes/elastic-cloud-serverless/index.md

@@ -11,6 +11,11 @@ Review the changes, fixes, and more to {{serverless-full}}.
 
 For {{serverless-full}} API changes, refer to [APIs Changelog](https://www.elastic.co/docs/api/changes).
 
+## June 26, 2025 [serverless-changelog-06262025]
+
+### Features and enhancements [serverless-changelog-06262025-features-enhancements]
+* {{serverless-full}} is now available in the Microsoft Azure `eastus` [region](/deploy-manage/deploy/elastic-cloud/regions.md). 
+
 ## June 23, 2025 [serverless-changelog-06232025]
 
 ### Features and enhancements [serverless-changelog-06232025-features-enhancements]
@@ -74,7 +79,6 @@ For {{serverless-full}} API changes, refer to [APIs Changelog](https://www.elast
 * Fixes **Discard** button state change logic for toggles [#223493]({{kib-pull}}223493)
 * Removes `originId` from connectors during rule import [#223454]({{kib-pull}}223454)
 
-
 ## June 17, 2025 [serverless-changelog-06172025]
 
 ### Features and enhancements [serverless-changelog-06172025-features-enhancements]