Website : Remove french comments

There is still a French comment (from Guillaume?) in the Severn_01: Set up of a semi-distributed GR model network page

nodes <- Severn$BasinsInfo[, c("gauge_id", "downstream_id", "distance_downstream", "area")]
nodes$distance_downstream <- nodes$distance_downstream #je ne comprends pas cette ligne, elle semble inutile
nodes$model <- "RunModel_GR4J"