Update git submodules

* Update docs/submodules/doctor from branch 'master'
  - [docs] fix link in danube release notes

    Change-Id: Idd02339dd8547359d4e73849b94e071fb6aeaaf1
    Signed-off-by: Ryota MIBU <r-mibu@cq.jp.nec.com>

diff --git a/docs/submodules/doctor b/docs/submodules/doctor
index bcffa7e..263682e 160000 (submodule)
--- a/docs/submodules/doctor
+++ b/docs/submodules/doctor
@@ -1 +1 @@
-Subproject commit bcffa7ef747c75a18d3b38182737222a6010ce36
+Subproject commit 263682e54a4d75d1f33c76735ffa2fe9debe0161