Add command socket support to zuul-scheduler

Bring online commandsocket support for the scheduler.

Change-Id: Ia1719650623e79d40f239776eb770550bb73169b
Signed-off-by: Paul Belanger <pabelanger@redhat.com>
diff --git a/doc/source/admin/components.rst b/doc/source/admin/components.rst
index 126e4e2..86b01ef 100644
--- a/doc/source/admin/components.rst
+++ b/doc/source/admin/components.rst
@@ -224,6 +224,11 @@
 
 .. attr:: scheduler
 
+   .. attr:: command_socket
+      :default: /var/lib/zuul/scheduler.socket
+
+      Path to command socket file for the scheduler process.
+
    .. attr:: tenant_config
       :required: