Adds a visible grid to the current page. The grid shows
locations on the page and the effect of the current transform. It
is designed to help with object positioning during development.
Example
The following code modifies the page transform and then adds a
grid to show how the transform has affected the page.
using var doc = new Doc();
doc.Page = doc.AddPage();
doc.Transform.Rotate(20, 100, 100);
doc.AddGrid();
doc.Save("docaddgrid.pdf");