buffet: Add some documentation to the Command interface

BUG=None
TEST=compiles

Change-Id: I8f6f55a774306dc4f76d3339f38eb43b6f8d39f4
Reviewed-on: https://chromium-review.googlesource.com/257040
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: David Zeuthen <zeuthen@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>

buffet/dbus_bindings/org.chromium.Buffet.Command.xml

diff --git a/buffet/dbus_bindings/org.chromium.Buffet.Command.xml b/buffet/dbus_bindings/org.chromium.Buffet.Command.xml
index 467be44..f5f24ef 100644
--- a/buffet/dbus_bindings/org.chromium.Buffet.Command.xml
+++ b/buffet/dbus_bindings/org.chromium.Buffet.Command.xml
@@ -11,12 +11,23 @@
       <annotation name="org.chromium.DBus.Method.Kind" value="normal"/>
     </method>
     <method name="Abort">
+      <tp:docstring>
+        Mark the command as aborted. This tells the cloud that the device did
+        not successfully complete executing the command.
+      </tp:docstring>
       <annotation name="org.chromium.DBus.Method.Kind" value="simple"/>
     </method>
     <method name="Cancel">
+      <tp:docstring>
+        Mark the command as cancelled. Unlike Abort() this should be used when
+        the device detects a user request to cancel a command.
+      </tp:docstring>
       <annotation name="org.chromium.DBus.Method.Kind" value="simple"/>
     </method>
     <method name="Done">
+      <tp:docstring>
+        Mark the command as successfully completed.
+      </tp:docstring>
       <annotation name="org.chromium.DBus.Method.Kind" value="simple"/>
     </method>
     <property name="Name" type="s" access="read"/>