[polari] main-window: Add tooltip to user list button

[Gitlab Administrative User <gitlab src gnome org>]

commit b9d2f7ae2986e559028732dad80d3c1d6f8ab1fe
Author: Daniel Boles <dboles src gmail com>
Date:   Tue Sep 12 22:41:48 2017 +0100

    main-window: Add tooltip to user list button
    
    https://bugzilla.gnome.org/show_bug.cgi?id=787154

 data/resources/main-window.ui | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/data/resources/main-window.ui b/data/resources/main-window.ui
index 8e61a11..6fde47e 100644
--- a/data/resources/main-window.ui
+++ b/data/resources/main-window.ui
@@ -168,6 +168,7 @@
                 <property name="visible">True</property>
                 <property name="focus-on-click">False</property>
                 <property name="action-name">app.user-list</property>
+                <property name="tooltip-text" translatable="yes">Show connected users</property>
                 <style>
                   <class name="polari-user-list-button"/>
                   <class name="text-button"/>