Update git submodules

* Update docs/submodules/releng from branch 'master'
  - Rework creating tags & branches from release files

    Old method could not properly handle both branching and
    tagging on changes to the release file.

    Proposed method:
    jjb calls:
    jjb/releng/branch-or-tag.sh
    for both verify and merge jobs.

    branch-or-tag determins nature of the change to
    "releases/branch/project.yaml"
    and calls
     releng-release-tagging.sh
    or
     releng-release-create-branch.sh

    The scripts above handle both verify and merge operations

    based on
      if [[ $TAG_EXISTS = false && "$JOB_NAME" =~ "merge" ]];
    and
      if [[ $REF_EXISTS = true && "$JOB_NAME" =~ "merge" ]]; then

    both scripts check that the ref exits in verfiy and merge stages.

    if releng-release-create-branch.sh creates a branch it then also
    calls releases/scripts/create_jobs.py

    Change-Id: Ieb99de5e4df100af59ecc818f52b0831383b2b62
    Signed-off-by: Aric Gardner <agardner@linuxfoundation.org>

diff --git a/docs/submodules/releng b/docs/submodules/releng
index 1569d33..52d29ad 160000 (submodule)
--- a/docs/submodules/releng
+++ b/docs/submodules/releng
@@ -1 +1 @@
-Subproject commit 1569d338abfadc2a851e7f842c3fcc22e2d7998d
+Subproject commit 52d29ad095ad729a0287ec07a2c19072b4fb672b