Prepare for 10.2.1 (#2484)

* Prepare for 10.2.1

* Update changelog

Author: nirinchev

CHANGELOG.md

@@ -1,4 +1,6 @@
-## vNext (TBD)
+## 10.2.1 (2021-06-30)
+
+This release changes the way Unity binaries are packaged and obviates the need to have an extra Unity package that contains the dependencies as standalone modules. If you were using the `io.realm.unity-bundled` package, please remove it and add the newly released `io.realm.unity` one.
 
 ### Fixed
 * \[Unity\] Fixed an issue where failing to weave an assembly due to modeling errors, would only show an error in the logs once and then fail opening a Realm with `No RealmObjects. Has linker stripped them?`. Now, the weaving errors will show up on every code change/weave attempt and the runtime error will explicitly suggest manually re-running the weaver. (Issue [#2310](https://github.com/realm/realm-dotnet/issues/2310))