add readme

Author: algompluecker

MongoDbTest/MongoDbConnection.cs

@@ -4,7 +4,7 @@ namespace MongoDbTest
 {
     public class MongoDbConnection : IAsyncLifetime
     {
-        private const string MongoConnectionString = "mongodb://127.0.0.1:27018";
+        private const string MongoConnectionString = "mongodb://127.0.0.1:27017";
 
         public MongoDbConnection()
         {

README.md

@@ -0,0 +1,5 @@
+This is a reproducer for an issue with the MongoDB C# driver tracked at https://jira.mongodb.org/browse/CSHARP-4488
+
+Please update the connection string in the class MongoDbConnection if necessary:
+
+    private const string MongoConnectionString = "mongodb://127.0.0.1:27017";