Prepare for release (#51885)

Author: JoshLove-msft

sdk/core/System.ClientModel/CHANGELOG.md

@@ -1,15 +1,15 @@
 # Release History
 
-## 1.6.0-beta.1 (Unreleased)
+## 1.6.0 (2025-08-11)
 
 ### Features Added
 
-### Breaking Changes
-
-### Bugs Fixed
+- Added `UserAgentPolicy` pipeline policy to allow adding the user agent to the request headers.
 
 ### Other Changes
 
+- Various updates to the `System.ClientModel.SourceGeneration` package to support `ModelReaderWriterBuildableAttribute`.
+
 ## 1.5.1 (2025-07-14)
 
 ### Bugs Fixed

sdk/core/System.ClientModel/src/System.ClientModel.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <Description>Contains building blocks for clients that call cloud services.</Description>
-    <Version>1.6.0-beta.1</Version>
+    <Version>1.6.0</Version>
     <!--The ApiCompatVersion is managed automatically and should not generally be modified manually.-->
     <ApiCompatVersion>1.5.1</ApiCompatVersion>
     <Nullable>enable</Nullable>
@@ -24,4 +24,4 @@
     <None Include="$(OutputPath)\..\..\System.ClientModel.SourceGeneration\$(Configuration)\netstandard2.0\System.ClientModel.SourceGeneration.dll" Pack="true" PackagePath="analyzers/dotnet/cs" Visible="false" />
   </ItemGroup>
 
-</Project>
+</Project>