Update license.php

Fixed typo.

src/www/license.php

@@ -64,7 +64,7 @@ $pgtitle = gettext("License");
             <br />
             OPNsense is a fork of <a href="http://www.pfsense.org" target="_blank">pfSense&reg;</a> <small>(Copyright &copy; 2004-2014 Electric Sheep Fencing, LLC. All rights reserved.)</small> a fork from <a href="http://m0n0.ch/wall" target="_blank">m0n0wall&reg;</a> <small>(Copyright &copy; 2002-2013 Manuel Kasper)</small>.<br />
             <br />
-            OPNsense includes various freely availbale software packages and ports.<br />
+            OPNsense includes various freely available software packages and ports.<br />
             The current ports are listed <a href="https://github.com/opnsense/tools/blob/master/config/current/ports.conf" target="_blank">here</a>.<br />
             <br />
             The authors of OPNsense would like to thank all contributors for their efforts.<br />