Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Set salt bootstrap distrib revision

    Change-Id: Id278afd05fd8793f573fce0d4ca1ff7420fc9127
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 8f3be16..caad7b5 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 8f3be1619a32b7c57f62a4b389e80b51b10b74a6
+Subproject commit caad7b5e20d66fafb391a37f2bfefc2e654dad6c