Filter out singleusergroup results from suggestions

If the singleusergroup plugin is installed alongside the reviewers
plugin, the reviewers plugin will suggest 'user/' groups from the
singleusergroup plugin despite not supporting them.

This change naively filters out 'user/' groups as the plugins are not
aware of each other.

Change-Id: I9bab8ea7db18d113b9f9a272b1ddef2ff4e0dd32
diff --git a/rv-reviewers/rv-reviewer.js b/rv-reviewers/rv-reviewer.js
index 66d1253..6145013 100644
--- a/rv-reviewers/rv-reviewer.js
+++ b/rv-reviewers/rv-reviewer.js
@@ -104,7 +104,9 @@
       if (!groups) { return []; }
       const groupSuggestions = [];
       for (const key in groups) {
-        if (!groups.hasOwnProperty(key)) { continue; }
+        if (!groups.hasOwnProperty(key) || key.startsWith('user/')) {
+          continue;
+        }
           name: key,
           value: key,
diff --git a/src/main/resources/Documentation/ b/src/main/resources/Documentation/
index 9de1838..93c466f 100644
--- a/src/main/resources/Documentation/
+++ b/src/main/resources/Documentation/
@@ -8,6 +8,12 @@
 to a change that is in `private` state. Reviewers will only be added to such a
 change if it transitions out of `private` state.
+This plugin automatically naively filters out groups that follow the style from
+the singleusergroup plugin.
+This means that groups that start with `user/` will not be suggested, regardless
+of source.