improve rain chart rounding

cmd/ingestd/web/index.html

@@ -66,6 +66,10 @@
             <div class="label">Rain 1h %</div>
             <div class="value" id="live-rain-prob">--</div>
           </div>
+          <div class="metric">
+            <div class="label">Rain hour mm</div>
+            <div class="value" id="live-rain-hour">--</div>
+          </div>
           <div class="metric">
             <div class="label">Wind m/s</div>
             <div class="value" id="live-wind">--</div>