Convert NEWS to UTF-8

* docs/news.xsl: request UTF-8 as the output encoding

* NEWS: re-generate with UTF-8 encoding

docs/news.xsl

 <?xml version="1.0"?>
 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                 version="1.0">
-  <xsl:output method="text" encoding="ISO-8859-1"/>
+  <xsl:output method="text" encoding="UTF-8"/>
 
   <xsl:template match="/">
     <xsl:text>