Update git submodules

* Update docs/submodules/fuel from branch 'master'
  - [docs] Bump release tag to 6.2.1

    Change-Id: I011f34535363d02ef726dfafd6abe0d3c6b4df5f
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 440f345..61783ae 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 440f345f1c51d7b5ffaff9bc9c86ba1561949c46
+Subproject commit 61783aec0db25652b11d6858b3103cc12d540b76