Fix minimum version

https://docs.microsoft.com/en-us/azure/cosmos-db/sql/sql-api-sdk-dotnet#recommended-version

changelog.md

@@ -1,6 +1,6 @@
 ## <a name="recommended-version"></a> Recommended version (Deprecated)
 
-The **minimum recommended version is [2.16.2](#2.16.2)**.
+The **minimum recommended version is [2.18.0](#2.18.0)**.
 
 **Note:**
 Because version 3 of the Azure Cosmos DB .NET SDK includes updated features and improved performance, we’ll retire version 2.x of this SDK on 31 August 2024.  As a result, you’ll need to update your SDK to version 3 by that date. We recommend following the [instructions](https://docs.microsoft.com/azure/cosmos-db/sql/migrate-dotnet-v3?tabs=dotnet-v3) to migrate to Azure Cosmos DB .NET SDK version 3.