Update git submodules

* Update docs/submodules/doctor from branch 'master'
  - Add process group so can kill possible hanging subprocesses.
    This should be workaround before actual fix is done.

    JIRA: DOCTOR-123

    Change-Id: I70fd4ed9d2aa2cc3a6c46e2515062b7acd31ca0a
    Signed-off-by: Tomi Juvonen <tomi.juvonen@nokia.com>

diff --git a/docs/submodules/doctor b/docs/submodules/doctor
index 888af5e..0974556 160000 (submodule)
--- a/docs/submodules/doctor
+++ b/docs/submodules/doctor
@@ -1 +1 @@
-Subproject commit 888af5e40c21c1cef22e968c076908f1601c53f2
+Subproject commit 0974556b87007373dfbfa3efa0c7659b5ce88abe