docs(pkgdown): update link for training session

vignettes/airGRiwrm.Rmd

@@ -16,6 +16,6 @@ knitr::opts_chunk$set(
 
 ## For getting started several materials are available:
 
-### [A slide-show of a training on **airGRiwrm** in French ](../training/fr/Formation_airGRiwrm.html)
+### [A slide-show of a training on **airGRiwrm** in French ](https://in-wop.gitlab.irstea.page/formation-airgriwrm/)
 ### [The vignettes provided with the package with example of use on the Severn River (UK)](index.html)
 ### [An example of use on a large network of 25 nodes on the Seine River (France)](index.html)