Update git submodules

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

    Change-Id: I011f34535363d02ef726dfafd6abe0d3c6b4df5f
    Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
    (cherry picked from commit 61783aec0db25652b11d6858b3103cc12d540b76)

diff --git a/docs/submodules/fuel b/docs/submodules/fuel
index 3fd2f2d..4ad7bc8 160000 (submodule)
--- a/docs/submodules/fuel
+++ b/docs/submodules/fuel
@@ -1 +1 @@
-Subproject commit 3fd2f2d4dc1d46495cf02041f95450664390e09b
+Subproject commit 4ad7bc825848153f38e321588e597f34d1472d6f