Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Merge "Rename pytest_suite_runner.py to unit.py"
  - Rename pytest_suite_runner.py to unit.py

    It also adds the rst files to include this module in apidoc.

    Change-Id: Iabbb17bc8601265bd9436c75d1afc0b470df1eb4
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>

diff --git a/docs/submodules/functest b/docs/submodules/functest
index 87570cf..9145722 160000 (submodule)
--- a/docs/submodules/functest
+++ b/docs/submodules/functest
@@ -1 +1 @@
-Subproject commit 87570cfe1261917a41a3aef287ecd30b928e841f
+Subproject commit 91457229e601b7f39b3a73d5db9f92397c1c8315