Update git submodules

* Update docs/submodules/so.git from branch 'master'
  to 18bcc4e72e339aa3fb584da7799e0071151b47c2
  - Merge "Updatable to false to prevent setting fk to null"
  - Updatable to false to prevent setting fk to null

    Updatable to false to prevent setting foreign key to null before delete

    Issue-ID: SO-2178
    Signed-off-by: Benjamin, Max (mb388a) <mb388a@att.com>
    Change-Id: I9b9f94c0d0b56a61cd8b9c56e80e5a3ec4819a50

diff --git a/docs/submodules/so.git b/docs/submodules/so.git
index b916336..18bcc4e 160000 (submodule)
--- a/docs/submodules/so.git
+++ b/docs/submodules/so.git
@@ -1 +1 @@
-Subproject commit b9163367a8760d5e4249fce287f638f1ec9dddfb
+Subproject commit 18bcc4e72e339aa3fb584da7799e0071151b47c2