Update notes for submitted changes

* Update orbit to S20210406213021 and add 4.20-staging target

91/b2e167a2341d41212ea801943fb82a148e3b7f

@@ -0,0 +1,7 @@
+Verified+1: JGit Bot <jgit-bot@eclipse.org>
+Code-Review+2: Matthias Sohn <matthias.sohn@sap.com>
+Submitted-by: Matthias Sohn <matthias.sohn@sap.com>
+Submitted-at: Sat, 10 Apr 2021 17:48:32 -0400
+Reviewed-on: https://git.eclipse.org/r/c/jgit/jgit/+/179148
+Project: jgit/jgit
+Branch: refs/heads/master