[docs] QDBusUtil::isValidObjectPath(): simplify description

The "does not contain two slashes in sequence" condition reads a bit
unmotivated. It's easier written as "each part is not empty", so do
that.

Pick-to: 6.7 6.6 6.5
Change-Id: Ibb204429521910582bd8ee03ff54f72d7e15ce84
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

src/dbus/qdbusutil.cpp

@@ -445,9 +445,8 @@ namespace QDBusUtil
         \list
           \li start with the slash character ("/")
           \li do not end in a slash, unless the path is just the initial slash
-          \li do not contain any two slashes in sequence
-          \li contain slash-separated parts, each of which is composed of ASCII letters, digits and
-             underscores ("_")
+          \li contain slash-separated parts, each of which is not empty, and composed
+              only of ASCII letters, digits and underscores ("_").
         \endlist
     */
     bool isValidObjectPath(const QString &path)