Update revision of singleusergroup plugin

- Add basic documentation

Change-Id: I2cb617dbca108cfd09438faba4f3dac583e5e51c
diff --git a/plugins/singleusergroup b/plugins/singleusergroup
index 141898f..b355c90 160000
--- a/plugins/singleusergroup
+++ b/plugins/singleusergroup
@@ -1 +1 @@
-Subproject commit 141898f9e160c190bdf28999e31f5c667a477f9c
+Subproject commit b355c909345e3ccf5ebb139ded538e35cbdbb67c