Add release notes for 1.25.2

Updates CHANGELOG.asciidoc

CHANGELOG.asciidoc

@@ -23,6 +23,19 @@ endif::[]
 [[release-notes-1.x]]
 === .NET Agent version 1.x
 
+[[release-notes-1.25.2]]
+==== 1.25.2
+
+This release fixes a bug in `Elastic.Apm.AspNetCore` when using ` UseElasticApm()` not correctly setting statuscodes.
+The bug was not present in the more commonly used `Elastic.Apm.NetCoreAll` since it used an `DiagnosticListener` approach.
+With this release we ensure both packages used the exact same mechanism to instrument ASP.NET Core.
+
+===== Bug fixes
+
+{pull}2213[#2213] Remove ApmMiddleWare, only use DiagnosticSource listener for ASP.NET Core.  
+{pull}2239[#2239] Move StartupHooks over to netstandard2.0.
+
+
 [[release-notes-1.25.1]]
 ==== 1.25.1