fix(graph panel): minor spelling change

public/app/panels/graph/axisEditor.html

@@ -190,10 +190,10 @@
 					Hide series
 				</li>
 				<li class="tight-form-item">
-					<editor-checkbox text="with only nulls" model="panel.legend.hideEmpty" change="render()"></editor-checkbox>
+					<editor-checkbox text="With only nulls" model="panel.legend.hideEmpty" change="render()"></editor-checkbox>
 				</li>
 				<li class="tight-form-item last">
-					<editor-checkbox text="with only zeroes" model="panel.legend.hideZero" change="render()"></editor-checkbox>
+					<editor-checkbox text="With only zeroes" model="panel.legend.hideZero" change="render()"></editor-checkbox>
 				</li>
 			</ul>
 			<div class="clearfix"></div>