Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - Merge "PDF: reclass: Rename template file suffix to _pdf"
  - PDF: reclass: Rename template file suffix to _pdf

    Init is a generic suffix which also collides with pre-existing files.
    A distinct suffix (e.g. _pdf) should be used.

    JIRA: FUEL-310

    Change-Id: I919a5394e7ff432ee86d10bafe889aeadb181649
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index a9fbe3c..b51c5f3 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit a9fbe3c47a680eded71680a4ee3b77b5e82af3c6
+Subproject commit b51c5f365f80cbad9f96d1c1c2c471a2d148414e