Update git submodules

* Update docs/submodules/releng from branch 'master'
  - xci: Enable multi-distro verify

    Change-Id: I82e5db83092b5f4d6f4ea25464f416ce879d4709
    Signed-off-by: Fatih Degirmenci <fatih.degirmenci@ericsson.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 0d28048..21cbe33 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 0d280485cc374957858bb3908ea42a4af7131fc5
+Subproject commit 21cbe335c3757a11d3c5b598b9f6cbedd1585fac