fixing broken link in map model documentation
//! Helpful terminology:
//! - ch = contraction hierarchy, for speeding up pathfinding
//! - degenerate intersection = only has 2 roads connected, so why is it an intersection at all?
-//! - lc = lane-change (which is modelled very strangely: <https://a-b-street.github.io/docs/tech/trafficsim/discrete_event.html#lane-changing>)
+//! - lc = lane-change (which is modelled very strangely: <https://a-b-street.github.io/docs/tech/trafficsim/discrete_event/index.html#lane-changing>)
//! - ltr = left-to-right, the order of lanes for a road
//! - osm = OpenStreetMap
//!
