Update git submodules

* Update docs/submodules/releng-xci from branch 'master'
  - Merge "Start documenting CI Loops and Confidence Loops applied by XCI"
  - Start documenting CI Loops and Confidence Loops applied by XCI

    Please note that the document you are about to review contains information
    about the existing CI Loops and promotion criterias applied by XCI in order
    to record the current state of affairs.

    Once this change gets merged, a new change will be proposed and that change
    will be the one where the existing criterias will be updated and the new ones
    will be introduced.

    This document is created to start the conversation around determining
    the promotion criterias (test scopes) for each of the current and upcoming
    CI Loops XCI uses.

    The expectation with this document is to update it collaboratively with
    scenario owners, projects, XCI Team, Test Projects, and Release Management
    to find the necessary level of testing as much as possible.

    The information this document contains and the criterias set in it will be
    superseded by the CD-Based Release model once it becomes available.

    Change-Id: I7b4afd87a4f7694eb78c996e7870b8dc1e833fbf
    Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>

diff --git a/docs/submodules/releng-xci b/docs/submodules/releng-xci
index ba83783..73f5018 160000 (submodule)
--- a/docs/submodules/releng-xci
+++ b/docs/submodules/releng-xci
@@ -1 +1 @@
-Subproject commit ba83783cb24bc3c40d9e43d97d7eeab4d88cb003
+Subproject commit 73f5018ee500401e774c42ea8f32b8db8a5146fd