Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Revert "Switch distrib revision to testing"

    There is no much difference between nightly vs testing repos.
    This reverts commit 052a1626da71d232431b3a9faf576a76db61f10e.

    Change-Id: I40f60ddc2c9e1e59c7c4eb0be59ae19b00b7fb9b
    Signed-off-by: Michael Polenchuk <mpolenchuk@mirantis.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index baccdc4..530987f 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit baccdc43292c3f33fd697e5b67b2867e2ea73c71
+Subproject commit 530987f59295ca04b340f5dc7fd2abc53839a85f