Update git submodules

* Update docs/submodules/openretriever from branch 'master'
  - upload NGVS requirements document

    Change-Id: Ice89740a34cb512fb94352fbb5104f4fdf589035
    Signed-off-by: Xuan Jia <jason.jiaxuan@gmail.com>

diff --git a/docs/submodules/openretriever b/docs/submodules/openretriever
index 5812982..263f77e 160000 (submodule)
--- a/docs/submodules/openretriever
+++ b/docs/submodules/openretriever
@@ -1 +1 @@
-Subproject commit 5812982c9b2c84aaa6bba36ac6a06ed025dd7e10
+Subproject commit 263f77ed215f0719e116b389019ce4116aff27f2