[NETBEANS-419] Fixed grammar in About dialog

https://issues.apache.org/jira/browse/NETBEANS-419

platform/o.n.core/src/org/netbeans/core/ui/Bundle.properties

@@ -18,7 +18,7 @@
 # Product Information panel
 LBL_Copyright=<div style="font-size: {0}pt; font-family: Verdana, 'Verdana CE',  Arial, 'Arial CE', 'Lucida Grande CE', lucida, 'Helvetica CE', sans-serif;">\
     NetBeans IDE and NetBeans Platform are based on Apache NetBeans from the Apache Software Foundation \
-    and is licensed under <a href="https://www.apache.org/licenses/LICENSE-2.0">\
+    and are licensed under <a href="https://www.apache.org/licenses/LICENSE-2.0">\
     Apache License Version 2.0</a>. For more information, please visit \
     <a href="https://netbeans.apache.org/">netbeans.apache.org</a>.</div>
 LBL_AddOnCopyright=<div style="font-size: {1}pt; font-family: Verdana, 'Verdana CE',  Arial, 'Arial CE', 'Lucida Grande CE', lucida, 'Helvetica CE', sans-serif;">\