adding instruction points to a route line using leaflet.js

i use leaflet.js to show a route in my web project. I have mastered everything successfully, except that I cannot display instruction points on the route.

i used the following code to show the Route on the map:

api.getRoute(routingLink).then(res =>{
    const routeLayer = L.geoJSON(res.data.features,{}).addTo(layerGroup) //shows route on the map 
})

my question is how can i add instruction points to the route that shows the instruction in popup on clicking it.

here a screenshot from the route:
shows the route between to places but not the instructions