fix typo in widgets in index.html

There was a small typo in the widgets description on index.html

index.html

@@ -76,7 +76,7 @@ <h2> Much more available as <strong>standard OntoPortal services...</strong></h2
 				<li>
 					<div class="service-circle square-image">Versioning</div>
 					<div class="name"></div>
-					<div class="position">Store all ontology versions, whether manually submitted or automatically pulled. Get diff betweem versions.</div>
+					<div class="position">Store all ontology versions, whether manually submitted or automatically pulled. Get diff between versions.</div>
 				</li>
 				<li>
 					<div class="service-circle square-image">Widgets</div>