Update graph.js

public/js/graph.js

@@ -18,6 +18,7 @@ function get_host(){
         }
     });
 }
+// get weather history CSV from server and load it into the DATA array.
 function get_history_weather(){
     $.ajax({
         type: 'GET',
@@ -32,6 +33,7 @@ function get_history_weather(){
         }
     });
 }
+// render graph with chartJS
 function make_graph(arr, depth=100){
     if (arr.length > 100){
         arr = [arr[0]].concat(arr.slice(-1 * depth));