[Changelogs] Contributor acknowledgments (Azure#53009)

* [Changelogs] Contributor acknowledgments

The focus of these changes is to update the
changelogs for Azure.Core and Service Bus to include
acknowledgments for our community contributors.

* Update sdk/core/Azure.Core/CHANGELOG.md

Co-authored-by: Copilot <[email protected]>

---------

Co-authored-by: Copilot <[email protected]>

Author: jsquire

sdk/core/Azure.Core/CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## 1.50.0-beta.1 (Unreleased)
 
+### Acknowledgments
+
+Thank you to our developer community members who helped to make the Azure.Core library better with their contributions to this release:
+
+- Daniel Marbach  _([GitHub](https://github.com/danielmarbach))_
+
 ### Features Added
 
 ### Breaking Changes
@@ -10,6 +16,8 @@
 
 ### Other Changes
 
+- Several performance and efficiency improvements were made to how request content is created and managed.   _([#52488](https://github.com/Azure/azure-sdk-for-net/pull/52488), a community contribution, courtesy of [danielmarbach](https://github.com/danielmarbach))_
+
 ## 1.49.0 (2025-09-22)
 
 ### Features Added

sdk/servicebus/Azure.Messaging.ServiceBus/CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## 7.21.0-beta.1 (Unreleased)
 
+### Acknowledgments
+
+Thank you to our developer community members who helped to make the Service Bus client library better with their contributions to this release:
+
+- Daniel Marbach  _([GitHub](https://github.com/danielmarbach))_
+
 ### Features Added
 
 ### Breaking Changes
@@ -10,6 +16,8 @@
 
 ### Other Changes
 
+- Several areas of the AMQP transport integration have been cleaned up, modernized, and made more efficient.  _(A community contribution, courtesy of [danielmarbach](https://github.com/danielmarbach))_
+
 ## 7.20.1 (2025-06-12)
 
 ### Bugs Fixed
@@ -246,6 +254,7 @@ Thank you to our developer community members who helped to make the Service Bus
 ## 7.13.0 (2023-03-08)
 
 ### Acknowledgments
+
 Thank you to our developer community members who helped to make the Service Bus client library better with their contributions to this release:
 
 - Daniel Marbach  _([GitHub](https://github.com/danielmarbach))_