doc: add release notes for breaking changes

Author: kwvg

doc/release-notes-7061.md

@@ -0,0 +1,8 @@
+# RPC changes
+
+- `quorum dkginfo` will now require that nodes run either in watch-only mode (`-watchquorums`) or as an
+  active masternode (i.e. masternode mode) as regular nodes do not have insight into network DKG activity.
+
+- `quorum dkgstatus` will no longer emit the return values `time`, `timeStr` and `session` on nodes that
+  do not run in either watch-only or masternode mode as regular nodes do not have insight into network
+  DKG activity.