Fixed typo in graphite editor tooltip

src/app/partials/graphite/editor.html

@@ -102,7 +102,7 @@
 					<input type="text"
 								class="input-mini grafana-target-segment-input"
 								ng-model="panel.cacheTimeout"
-								bs-tooltip="'Graphite parameter to overwride memcache default timeout (unit is seconds)'"
+								bs-tooltip="'Graphite parameter to override memcache default timeout (unit is seconds)'"
 								data-placement="right"
 								spellcheck='false'
 								placeholder="60">