add missing license header in #314 / DS-1683

dspace-api/src/main/java/org/dspace/discovery/SolrServiceSpellIndexingPlugin.java

@@ -1,3 +1,10 @@
+/**
+ * The contents of this file are subject to the license and copyright
+ * detailed in the LICENSE and NOTICE files at the root of the source
+ * tree and available online at
+ *
+ * http://www.dspace.org/license/
+ */
 package org.dspace.discovery;
 
 import org.apache.solr.common.SolrInputDocument;