[cheese] Add documentation for new API

[David King <davidk src gnome org>]

commit 054c14aa6c97a99511b95f628984701ff2a45117
Author: David King <amigadave amigadave com>
Date:   Mon Sep 21 09:56:44 2020 +0100

    Add documentation for new API
    
    Add gtk-doc documentation for
    cheese_camera_device_supported_format_caps().

 docs/reference/cheese-sections.txt | 1 +
 libcheese/cheese-camera-device.c   | 7 +++++++
 2 files changed, 8 insertions(+)
---
diff --git a/docs/reference/cheese-sections.txt b/docs/reference/cheese-sections.txt
index 9dd5a480..842d2de2 100644
--- a/docs/reference/cheese-sections.txt
+++ b/docs/reference/cheese-sections.txt
@@ -98,6 +98,7 @@ cheese_camera_device_get_best_format
 cheese_camera_device_get_caps_for_format
 cheese_camera_device_get_format_list
 cheese_camera_device_get_src
+cheese_camera_device_supported_format_caps
 <SUBSECTION Private>
 CheeseCameraDevicePrivate
 CheeseCameraDeviceClass
diff --git a/libcheese/cheese-camera-device.c b/libcheese/cheese-camera-device.c
index c6cc39ef..6d91bd9e 100644
--- a/libcheese/cheese-camera-device.c
+++ b/libcheese/cheese-camera-device.c
@@ -947,6 +947,13 @@ cheese_camera_device_get_caps_for_format (CheeseCameraDevice *device,
     return result_caps;
 }
 
+/**
+ * cheese_camera_device_supported_format_caps:
+ *
+ * Get the #GstCaps that are supported for all #CheeseCameraDevice
+ *
+ * Returns: (transfer full): the #GstCaps
+ */
 GstCaps *
 cheese_camera_device_supported_format_caps (void)
 {