update ag-grid section

Update the AG Grid section for the custom components 

docs:  https://www.dash-mantine-components.com/dash-ag-grid

discussion:  https://github.com/snehilvj/dash-mantine-components/discussions/467#discussioncomment-14998036
updated example on pycafe : https://py.cafe/dash.mantine.components/dash-ag-grid-dmc-cell-editors

