Make tables of contents in long sections sections

[knstvk]

Environment

• Documentation version: 7.2
• Part of the documentation: Manual
• Existing page: http://localhost:6080/manual-7.2/gui_Table.html http://localhost:6080/manual-7.2/gui_DataGrid.html

Description of the bug or enhancement

TOC should list links to subsections like "dataGrid elements", "dataGrid attributes", etc.