chore: add a note about upgrading Microsoft.CodeAnalysis.CSharp dep

Signed-off-by: Rui Chen <[email protected]>

src/Kiota.Generated/KiotaGenerated.csproj

@@ -9,6 +9,10 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <!-- NOTE: This version constraint (4.8.0.0) MUST match the earliest version supported for .NET 8 to prevent compatibility issues with the SDK.
+            Updating this version might cause runtime errors due to unsupported dependencies in older SDK versions.
+            Please avoid upgrading this dependency unless the target framework version is changed or until confirmed compatible with .NET 8.
+            If Dependabot suggests an upgrade, it should be ignored. -->
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.8.0.0"
       ExcludeAssets="runtime" />
     <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4"