Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "lib.sh: Fix compatibility with bash 4.2"
  - lib.sh: Fix compatibility with bash 4.2

    JIRA: FUEL-296

    Change-Id: Ide9f9333fe9b44ff6b78678064f8e67f05aabd42
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index ab9d5af..ac4530f 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit ab9d5af063c243d3201b9405f8781515a08ce0f3
+Subproject commit ac4530fa1c89ff1a6af3cec09b3b5de458426bde