Influxdb datasource: fix language in stacking helpful info section (#8134)

public/app/plugins/datasource/influxdb/partials/query.options.html

@@ -54,7 +54,7 @@
 		<div class="grafana-info-box span6" ng-if="ctrl.panelCtrl.editorHelpIndex === 2">
 			<h5>Stacking and fill</h5>
 			<ul>
-				<li>When stacking is enabled it important that points align</li>
+				<li>When stacking is enabled it is important that points align</li>
 				<li>If there are missing points for one series it can cause gaps or missing bars</li>
 				<li>You must use fill(0), and select a group by time low limit</li>
 				<li>Use the group by time option below your queries and specify for example &gt;10s if your metrics are written every 10 seconds</li>