Update ref doc copyright year

docs/manual/src/docs/asciidoc/index-docinfo.xml

@@ -1,7 +1,7 @@
 <productname>Spring Security</productname>
 <releaseinfo>{spring-security-version}</releaseinfo>
 <copyright>
-	<year>2004-2017</year>
+	<year>2004-2019</year>
 </copyright>
 <legalnotice>
 	<para>Copies of this document may be made for your own use and for distribution to