Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Get latest salt-formulas code

    Change-Id: I6284589343bfcdc4f35734d5c291ad0a2bf02d74
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 3c7e4c3..8f3be16 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 3c7e4c3773face367cdf0988cccfc2dfd68f55ab
+Subproject commit 8f3be1619a32b7c57f62a4b389e80b51b10b74a6