Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Cleanup outdated salt keys

    Remove keys that are left over from the previous deployment
    to avoid interfere with the new ones.

    Change-Id: I0dfa9782cbce9a8e8b7c1efe5954c8ffe85996f9
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index c77e7e7..b24bbb9 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit c77e7e79f11af144275feb3237de07d5fc79f2f6
+Subproject commit b24bbb99bdf5c09273e360aabf85b2c84573326e