Update git submodules

* Update docs/submodules/doctor from branch 'master'
  - add __init__.py file in doctor_tests dir

    Change-Id: I43bd8aaadec893114b00d10c3f36dafd8bcef21e
    Signed-off-by: dongwenjuan <dong.wenjuan@zte.com.cn>

diff --git a/docs/submodules/doctor b/docs/submodules/doctor
index 25759e0..54b4b34 160000 (submodule)
--- a/docs/submodules/doctor
+++ b/docs/submodules/doctor
@@ -1 +1 @@
-Subproject commit 25759e0a0204765a7a9454d7586df66592e943c2
+Subproject commit 54b4b3418aae6d649411b531f0aa8bc4d9fd6b2c