[libmanette] device: Document *_set_mapping()

[Adrien Plazas <aplazas src gnome org>]

commit 1f4776f48c91078af1a1722629d374b64920f6f4
Author: vanadiae <vanadiae35 gmail com>
Date:   Wed Oct 14 19:42:07 2020 +0200

    device: Document *_set_mapping()

 src/manette-device.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
---
diff --git a/src/manette-device.c b/src/manette-device.c
index bbdecd2..69b4bef 100644
--- a/src/manette-device.c
+++ b/src/manette-device.c
@@ -732,7 +732,14 @@ manette_device_get_version_id (ManetteDevice *self)
   return libevdev_get_id_version (self->evdev_device);
 }
 
-// FIXME documentation
+/**
+ * manette_device_set_mapping:
+ * @self: a #ManetteDevice
+ * @mapping: a #ManetteMapping
+ *
+ * Associate @mapping to @self to map its hardware events into standard gamepad
+ * ones.
+ */
 void
 manette_device_set_mapping (ManetteDevice  *self,
                             ManetteMapping *mapping)