update date in panel

frontend/src/Sidebar/index.jsx

@@ -153,7 +153,7 @@ function Welcome(){
         <h2>Toronto Historic Travel Times</h2>
         <p>
             This application allows you to query averaged motor vehicle travel
-            times across the city, as far back as 2017. Data come from a small
+            times across the city, as far back as 2017-09-01. Data come from a small
             sample of probe vehicles that report their location data 
             to <a href="https://www.here.com/">Here</a>. For more information on
             this application and our methodology