add v0.11.1-beta.1 changelog

Signed-off-by: Steve Kriss <krisss@vmware.com>

changelogs/CHANGELOG-0.11.md

@@ -1,4 +1,11 @@
-  - [v0.11.0](#v0110)
+## v0.11.1-beta.1
+#### 2019-05-03
+
+### Download
+- https://github.com/heptio/velero/releases/tag/v0.11.1-beta.1
+
+### Highlights
+* Added the `velero migrate-backups` command to migrate legacy Ark backup metadata to the current Velero format in object storage. This command needs to be run in preparation for upgrading to v1.0, **if** you have backups that were originally created prior to v0.11 (i.e. when the project was named Ark).
 
 ## v0.11.0
 #### 2019-02-28