Update git submodules

* Update docs/submodules/functest from branch 'stable/fraser'
  - Check API doc via doc8

    It also cleans unseless dirs.

    Change-Id: I13be1359b36c49e8f199087fe2a23818c6d1b6e0
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
    (cherry picked from commit 4fdae297551f0d1be07cf2edd39e3428923b52ae)

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 9d4c993..1827833 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 9d4c993b94dfb6d46064531db032d157f4a0aebf
+Subproject commit 18278331ef05693d3ecf123bc74f14f6cd07ec13