Improve documentation of wxAuiPaneInfo direction-related methods

Mention the corresponding flag in the documentation of all helper
functions, not just some of them.

Closes #9722.

Closes https://github.com/wxWidgets/wxWidgets/pull/1388

interface/wx/aui/framemanager.h

@@ -889,6 +889,7 @@ public:
 
     /**
         Right() sets the pane dock position to the right side of the frame.
+        This is the same thing as calling Direction(wxAUI_DOCK_RIGHT).
     */
     wxAuiPaneInfo& Right();
 
@@ -932,6 +933,7 @@ public:
 
     /**
         Top() sets the pane dock position to the top of the frame.
+        This is the same thing as calling Direction(wxAUI_DOCK_TOP).
     */
     wxAuiPaneInfo& Top();