[libgudev] gudev: Add note about possible actions

[Bastien Nocera <hadess src gnome org>]

commit 39c282913e74ec1259b9b695fc6abed0d8503753
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Sep 7 13:47:15 2017 +0200

    gudev: Add note about possible actions
    
    https://bugzilla.gnome.org/show_bug.cgi?id=787314

 gudev/gudevclient.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gudev/gudevclient.c b/gudev/gudevclient.c
index 4436c46..8c204c3 100644
--- a/gudev/gudevclient.c
+++ b/gudev/gudevclient.c
@@ -291,6 +291,9 @@ g_udev_client_class_init (GUdevClientClass *klass)
    * for the majority of actions, only the sysfs path will be available when the device
    * is removed.
    *
+   * Also note that the action is an arbitrary string, controlled by device drivers. Other
+   * values than those listed is possible, but unlikely.
+   *
    * This signal is emitted in the
    * <link linkend="g-main-context-push-thread-default">thread-default main loop</link>
    * of the thread that @client was created in.