fix the bug with the current path being restored if it was under the group being deleted with DeleteGroup(); clarify what happens in this case in the docs

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@40095 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/fileconf.cpp

@@ -1145,6 +1145,8 @@ bool wxFileConfig::DeleteGroup(const wxString& key)
   if ( !m_pCurrentGroup->DeleteSubgroupByName(path.Name()) )
       return false;
 
+  path.UpdateIfDeleted();
+
   SetDirty();
 
   return true;