Update changelog for beta.8 release (#34678)

Author: vishweshbankwar

sdk/monitor/Azure.Monitor.OpenTelemetry.Exporter/CHANGELOG.md

@@ -1,21 +1,23 @@
 # Release History
 
-## 1.0.0-beta.8 (Unreleased)
+## 1.0.0-beta.8 (2023-03-07)
 
 ### Features Added
 
 * AAD can now be configured via `AzureMonitorExporterOptions`
   ([#34555](https://github.com/Azure/azure-sdk-for-net/pull/34555))
 
+* Connection String can now be provided via
+  `APPLICATIONINSIGHTS_CONNECTION_STRING` environment variable
+  ([#34275](https://github.com/Azure/azure-sdk-for-net/pull/34275))
+
 * `dependencies\duration` and `requests\duration` standard metrics will now be
   exported by default when trace exporter is used alongside metric exporter
   ([#34010](https://github.com/Azure/azure-sdk-for-net/pull/34010))
   ([#33999](https://github.com/Azure/azure-sdk-for-net/pull/33999))
 
 * Added support for named options ([#33803](https://github.com/Azure/azure-sdk-for-net/pull/33803))
 
-### Breaking Changes
-
 ### Bugs Fixed
 
 * Fixed an issue of missing logs due to unhandled exception. ([#34423](https://github.com/Azure/azure-sdk-for-net/pull/34423))