Update git submodules

* Update docs/submodules/releng from branch 'master'
  to 171886d18920a9de283a3b4999c140eea6e312f8
  - Create pieman jobs

    Change-Id: I1ec9691cb610881f3037eca82c3a3e523a4bc1f1
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 0dcd8dd..171886d 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 0dcd8dd23ef1352bf0a99d4244fd73808d067e5e
+Subproject commit 171886d18920a9de283a3b4999c140eea6e312f8