Update git submodules

* Update docs/submodules/doctor from branch 'stable/fraser'
  - Fraser 6.1.0

    Change-Id: Id26ebd8438f26f60efe3f433e6c46ae76ab95d4a
    Signed-off-by: Tomi Juvonen <tomi.juvonen@nokia.com>
    (cherry picked from commit db301edb5a06109628af0b2e3416751615f11153)

diff --git a/docs/submodules/doctor b/docs/submodules/doctor
index cd50072..c91aa72 160000 (submodule)
--- a/docs/submodules/doctor
+++ b/docs/submodules/doctor
@@ -1 +1 @@
-Subproject commit cd500723c3b2de3655b2dc56ea9647f358183264
+Subproject commit c91aa72e7df34ec3416be3c9f73f7484a91312fb