Update git submodules

* Update docs/submodules/doctor from branch 'master'
  - Fix session error with INSPECTOR_TYPE=congress

    In monitor.py, the self.session value is not defined
    in DoctorMonitorSample class. This commit fixes it.

    JIRA: DOCTOR-111

    Change-Id: Ib61caa4146d78d6fe4857299c4730f13a7ac7a27
    Signed-off-by: Umar Farooq <umar.farooq@neclab.eu>

diff --git a/docs/submodules/doctor b/docs/submodules/doctor
index b261479..7ad77a7 160000 (submodule)
--- a/docs/submodules/doctor
+++ b/docs/submodules/doctor
@@ -1 +1 @@
-Subproject commit b2614799f404ed44b19d5dbc7c0b6229071c87bb
+Subproject commit 7ad77a7c4970056c3be42bc2aec5cb5322154cdb