add upgrade info to readme

Author: stephenatsembit

src/DataStax.AstraDB.DataApi/README.md

@@ -8,6 +8,33 @@ This C# Client Library simplifies using the DataStax Data API to manage and inte
 dotnet add package DataStax.AstraDB.DataApi
 ```
 
+# Upgrade to 2.0.1-beta
+
+If you were on a previous version of the beta, please note the following breaking change. When setting various options for a Collection or Table Find command, all of the options are chained to the Find command. The DocumentFindManyOptions parameter is no longer needed (and has been removed from the SDK)
+
+Instead of this:
+```
+        var findOptions = new DocumentFindManyOptions<SimpleObject>()
+        {
+            Sort = sort,
+            Limit = 1,
+            Skip = 2,
+            Projection = inclusiveProjection
+        };
+        var results = collection.Find(filter, findOptions).ToList();
+```
+
+Now do this:
+```
+        var results = collection.Find(filter)
+            .Sort(sort)
+            .Skip(2)
+            .Limit(1)
+            .Project(inclusiveProjection)
+            .ToList();
+```
+
+
 # Quickstart
 
 ```