DOC: include explanation of non-noded intersections in documentation of polygonize

I spent some time today banging my head against the wall trying to figure out how to ensure that polygonize returns all expected polygons and found out that non-noded intersections (non-planar network like briges or tunnels intersecting streets on the ground) very often cause a trouble. And then I found out how to fix that.

The whole thing is described here but the key trick is to use node before polygonize to ensure the proper result.

collection = shapely.GeometryCollection(linestrings_array)  # combine to a single object
noded = shapely.node(collection)  # add missing nodes
polygonized = shapely.polygonize(noded.geoms)  # polygonize based on an array of nodded parts

I was wondering if it shouldn't be part of the documentation so others don't have to through the same process as I did. Happy to do a PR but wanted to check first.

Start with the polygonize documentation and the linked explanation of non-noded intersections. Add guidance that non-planar networks can omit polygons and document the node-before-polygonize approach shown in the issue; done when users can find and follow this example.