Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "[baremetal] package: install python-yaml"
  - [baremetal] package: install python-yaml

    - Required for PDF parsing

    Change-Id: I95205e62efab3e9920687866d3a53a135828a218
    Signed-off-by: Taseer Ahmed <taseer94@gmail.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index d811bb3..9e231d1 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit d811bb37767e78907bfdaedfc3e7fe723179e728
+Subproject commit 9e231d1918d037902021aa92d0eca557bd1c5d3c