Expand the path docs a bit

docs/reference/gsk/paths.md

@@ -132,3 +132,19 @@ To obtain a `GskPathPoint`, use [method@Gsk.Path.get_closest_point], [method@Gsk
 To query properties of the path at a point, use [method@Gsk.PathPoint.get_position],
 [method@Gsk.PathPoint.get_tangent], [method@Gsk.PathPoint.get_rotation] and
 [method@Gsk.PathPoint.get_curvature].
+
+## Going beyond GskPath
+
+Lots of powerful functionality can be implemented for paths:
+
+- Finding intersections
+- Offsetting curves
+- Molding curves (making them pass through a given point)
+
+GSK does not provide API for all of these, but it does offer a way to get at
+the underlying Bézier curves, so you can implement such functionality yourself.
+You can use [method@Gsk.Path.foreach] to iterate over the operations of the
+path, and get the points needed to reconstruct or modify the path piece by piece.
+
+See e.g. the [Primer on Bézier curves](https://pomax.github.io/bezierinfo/)
+for inspiration of useful things to explore.