docs: add link to Level Viewport

docs/level_editor/level_editor.rst

@@ -19,7 +19,7 @@ Number Name                    What it shows
 2      Console                 Messages from the Level Editor, the Game and other Runtimes.
 3      Inspector               The properties of the currently selected object.
 4      Level Tree              A hierarchical view of all the objects in the Level.
-5      Level Viewport          The Level being edited.
+5      :ref:`Level Viewport`   The Level being edited.
 6      Menubar                 Common commands for editing / debugging / opening editors etc.
 7      Toolbar                 Tools and common options for editing.
 8      Statusbar               Contextual info and small self-contained messages.