Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - submodule: pharos: Bump to fix run without eyaml

    Most Fuel PODs do not use encrypted PDFs, so bump Pharos git
    submodule to include updated `generate_config.py` to silently
    skip decryption in case eyaml is not installed.

    Change-Id: I845a32c7001123a93e38197e0daf53d18c797aed
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 9136aef..8c15c36 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 9136aef95f77a1f26175929caedfe6ae662bbbd8
+Subproject commit 8c15c3675d57bfaed9c6923ed8adfdb6879fea49