13-transport.Rmd: fix typo (valhallr)

13-transport.Rmd

@@ -483,7 +483,7 @@ Changing route network characteristics (or weights associated with different rou
 ### Locally hosted dedicated routing engines {#localengine}
 
 **Locally hosted** routing engines include OpenTripPlanner, [Valhalla](https://github.com/valhalla/valhalla), and R5 (which are multi-modal), and the OpenStreetMap Routing Machine (OSRM) (which is 'uni-modal').
-These can be accessed from R with the packages **opentripplanner**, [**valhalla**](https://github.com/chris31415926535/valhallr), **r5r** and [**osrm**](https://github.com/riatelab/osrm) [@morgan_opentripplanner_2019; @pereira_r5r_2021].
+These can be accessed from R with the packages **opentripplanner**, [**valhallr**](https://github.com/chris31415926535/valhallr), **r5r** and [**osrm**](https://github.com/riatelab/osrm) [@morgan_opentripplanner_2019; @pereira_r5r_2021].
 Locally hosted routing engines run on the user's computer but in a process separate from R.
 They benefit from speed of execution and control over the weighting profile for different modes of transport.
 Disadvantages include the difficulty of representing complex networks locally; temporal dynamics (primarily due to traffic); and the need for specialized external software.