all it means is you really have to only swop the coordinates out.
so I have this:
library(sf)
library(leaflet)
#method one
points <- data.frame(lat = c(38.77813955,38.77202007),lng= c(-1.833538909,-1.842456068))
points <- st_as_sf(points,coords = c('lat','lng'))
leaflet(data = points) %>%
addProviderTiles(provider = providers$OpenStreetMap.Mapnik) %>%
addMarkers()
#method two
points <- data.frame(lat = c(38.77813955,38.77202007,38.77813955,38.77202007),lng= c(-1.833538909,-1.842456068,-1.842456068,-1.833538909))
leaflet(data = points) %>%
addProviderTiles(provider = providers$OpenStreetMap.Mapnik) %>%
addMarkers()