docs: Move the GDBusError SECTION

Adding it all to the docs for the `GDBusError` enum seemed a bit much,
so I moved it to its own content page.

Signed-off-by: Philip Withnall <pwithnall@gnome.org>

Helps: #3037

gio/gdbuserror.c

@@ -33,82 +33,6 @@
 
 #include "glibintl.h"
 
-/**
- * SECTION:gdbuserror
- * @title: GDBusError
- * @short_description: Mapping D-Bus errors to and from GError
- * @include: gio/gio.h
- *
- * All facilities that return errors from remote methods (such as
- * g_dbus_connection_call_sync()) use #GError to represent both D-Bus
- * errors (e.g. errors returned from the other peer) and locally
- * in-process generated errors.
- *
- * To check if a returned #GError is an error from a remote peer, use
- * g_dbus_error_is_remote_error(). To get the actual D-Bus error name,
- * use g_dbus_error_get_remote_error(). Before presenting an error,
- * always use g_dbus_error_strip_remote_error().
- *
- * In addition, facilities used to return errors to a remote peer also
- * use #GError. See g_dbus_method_invocation_return_error() for
- * discussion about how the D-Bus error name is set.
- *
- * Applications can associate a #GError error domain with a set of D-Bus errors in order to
- * automatically map from D-Bus errors to #GError and back. This
- * is typically done in the function returning the #GQuark for the
- * error domain:
- * |[<!-- language="C" -->
- * // foo-bar-error.h:
- *
- * #define FOO_BAR_ERROR (foo_bar_error_quark ())
- * GQuark foo_bar_error_quark (void);
- *
- * typedef enum
- * {
- *   FOO_BAR_ERROR_FAILED,
- *   FOO_BAR_ERROR_ANOTHER_ERROR,
- *   FOO_BAR_ERROR_SOME_THIRD_ERROR,
- *   FOO_BAR_N_ERRORS / *< skip >* /
- * } FooBarError;
- *
- * // foo-bar-error.c:
- *
- * static const GDBusErrorEntry foo_bar_error_entries[] =
- * {
- *   {FOO_BAR_ERROR_FAILED,           "org.project.Foo.Bar.Error.Failed"},
- *   {FOO_BAR_ERROR_ANOTHER_ERROR,    "org.project.Foo.Bar.Error.AnotherError"},
- *   {FOO_BAR_ERROR_SOME_THIRD_ERROR, "org.project.Foo.Bar.Error.SomeThirdError"},
- * };
- *
- * // Ensure that every error code has an associated D-Bus error name
- * G_STATIC_ASSERT (G_N_ELEMENTS (foo_bar_error_entries) == FOO_BAR_N_ERRORS);
- *
- * GQuark
- * foo_bar_error_quark (void)
- * {
- *   static gsize quark = 0;
- *   g_dbus_error_register_error_domain ("foo-bar-error-quark",
- *                                       &quark,
- *                                       foo_bar_error_entries,
- *                                       G_N_ELEMENTS (foo_bar_error_entries));
- *   return (GQuark) quark;
- * }
- * ]|
- * With this setup, a D-Bus peer can transparently pass e.g. %FOO_BAR_ERROR_ANOTHER_ERROR and
- * other peers will see the D-Bus error name org.project.Foo.Bar.Error.AnotherError.
- *
- * If the other peer is using GDBus, and has registered the association with
- * g_dbus_error_register_error_domain() in advance (e.g. by invoking the %FOO_BAR_ERROR quark
- * generation itself in the previous example) the peer will see also %FOO_BAR_ERROR_ANOTHER_ERROR instead
- * of %G_IO_ERROR_DBUS_ERROR. Note that GDBus clients can still recover
- * org.project.Foo.Bar.Error.AnotherError using g_dbus_error_get_remote_error().
- *
- * Note that the %G_DBUS_ERROR error domain is intended only
- * for returning errors from a remote message bus process. Errors
- * generated locally in-process by e.g. #GDBusConnection should use the
- * %G_IO_ERROR domain.
- */
-
 static const GDBusErrorEntry g_dbus_error_entries[] =
 {
   {G_DBUS_ERROR_FAILED,                           "org.freedesktop.DBus.Error.Failed"},