unclear instructions and example for building an OSM road network

[robfitzgerald]

i'm looking at our example and there's no documentation on what the schema of the geojson is supposed to be. i'm assuming it's reading the output of an OSMNx network but i'm not clear on how. Or, maybe it's just a polygon?

we should update this example so it more clearly describes a simple pipeline for building networks. we should ideally assign speeds based on 1) labeled speeds, 2) average labeled speed by road class. handled by osmnx

[robfitzgerald]

ok, just dove through to see the code uses osmnx under-the-hood to read in a network, so, this task is pretty simple just adding the comment that the expected geometry is the extent of the road network to retrieve from OSM