Update git submodules

* Update docs/submodules/doctor from branch 'stable/euphrates'
  - Merge "fix collectd's bug" into stable/euphrates
  - fix collectd's bug

    After we move files under doctor_tests and install doctor package,
    the tests/lib/monitors/collectd/collectd_plugin.py file will not be
    in the doctor_tests package.

    Change-Id: I24a098e26ea3cd257f2376458d5c31ecc87aac68
    Signed-off-by: dongwenjuan <dong.wenjuan@zte.com.cn>
    (cherry picked from commit a321477d00ccb84b0d99e7476e4306605498409d)

diff --git a/docs/submodules/doctor b/docs/submodules/doctor
index 0bf5977..e2caf1d 160000 (submodule)
--- a/docs/submodules/doctor
+++ b/docs/submodules/doctor
@@ -1 +1 @@
-Subproject commit 0bf59774ecfd4c92f1491b29aea9d116f0d92943
+Subproject commit e2caf1d81307bc3c0db391ca8129a585b5c06e8d