Upgrade file

Author: GromNaN

UPGRADE-2.0.md

@@ -4,6 +4,18 @@ UPGRADE FROM 1.x to 2.0
  * Classes in the namespace `MongoDB\Operation\` are `final`.
  * All methods in interfaces and classes now define a return type.
 
+Operations with no result
+-------------------------
+
+The following operations no longer return the raw command result. The return
+type changed to `void`. In case of an error, an exception is thrown.
+
+ * `MongoDB\Client`: `dropDatabase`
+ * `MongoDB\Collection`: `drop`, `dropIndex`, `dropIndexes`, `dropSearchIndex`, `rename`
+ * `MongoDB\Database`: `createCollection`, `createEncryptedCollection`, `drop`, `dropCollection`, `modifyCollection`, `renameCollection`
+
+If you still need to access the raw command result, you can use a `CommandSubscriber`.
+
 GridFS
 ------