Update git submodules

* Update docs/submodules/aaf/certservice.git from branch 'master'
  to 892eb3fb564c2d7c50e2ecb0494bbc599f5f7ae4
  - Update css file name in conf.py
    
    ribbon.css is the correct name of the css file.
    
    Issue-ID: CIMAN-376
    Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>
    Change-Id: Ia8f9eda20890a92545b15d40bb76f4f1ed627006
    
diff --git a/docs/submodules/aaf/certservice.git b/docs/submodules/aaf/certservice.git
index 60acf48..892eb3f 160000
--- a/docs/submodules/aaf/certservice.git
+++ b/docs/submodules/aaf/certservice.git
@@ -1 +1 @@
-Subproject commit 60acf480b78b442b45d229774c258f2dd9dc25d7
+Subproject commit 892eb3fb564c2d7c50e2ecb0494bbc599f5f7ae4