router.project-osrm.org only offers a car routing service. You can change the word “driving” to “foot” or “cycle” or “giant_badger” if you like but it won’t make any difference - you’ll still only get a car route.
If you want to run a foot router, you’ll either have to set up your own instance of OSRM, or use another service (such as Graphhopper or Mapzen).