Doc: Correct paths for designer plugins on OS X

Change-Id: Ia0ebd0539513d38acd97e834465cc3ea6da90a6e
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>

doc/src/widgets/qtdesigner-plugins.qdoc

@@ -101,9 +101,9 @@
             \list
 
                 \li \c {libqwt_designer_plugin.dylib} to
-                    \c {QtCreator.app/Contents/MacOS/designer}
+                    \c {Qt Creator.app/Contents/PlugIns/designer}
 
-                \li  \c {libqwt.*.dylib} to \c {QtCreator.app/Contents/Frameworks}
+                \li  \c {libqwt.*.dylib} to \c {Qt Creator.app/Contents/Frameworks}
 
             \endlist