[devhelp] docs: improve doc of the "profile" properties

[Sébastien Wilmet <swilmet src gnome org>]

commit aabb5c6018ef18aea70ee59911652d5a08377591
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Thu Apr 5 15:43:12 2018 +0200

    docs: improve doc of the "profile" properties

 devhelp/dh-book-tree.c |    3 ++-
 devhelp/dh-sidebar.c   |    3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/devhelp/dh-book-tree.c b/devhelp/dh-book-tree.c
index 3090373..285463e 100644
--- a/devhelp/dh-book-tree.c
+++ b/devhelp/dh-book-tree.c
@@ -851,7 +851,8 @@ dh_book_tree_class_init (DhBookTreeClass *klass)
         /**
          * DhBookTree:profile:
          *
-         * The #DhProfile.
+         * The #DhProfile. If set to %NULL, the default profile as returned by
+         * dh_profile_get_default() is used.
          *
          * Since: 3.30
          */
diff --git a/devhelp/dh-sidebar.c b/devhelp/dh-sidebar.c
index e7f8beb..9f057e8 100644
--- a/devhelp/dh-sidebar.c
+++ b/devhelp/dh-sidebar.c
@@ -659,7 +659,8 @@ dh_sidebar_class_init (DhSidebarClass *klass)
         /**
          * DhSidebar:profile:
          *
-         * The #DhProfile.
+         * The #DhProfile. If set to %NULL, the default profile as returned by
+         * dh_profile_get_default() is used.
          *
          * Since: 3.30
          */