Better BOM docs.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/csv/trunk@1638121 13f79535-47bb-0310-9956-ffa450edef68

Author: garydgregory

src/site/xdoc/user-guide.xml

@@ -49,6 +49,15 @@ try {
 } finally {
     parser.close();
     reader.close();
+}</source>
+  <p>
+    You might find it handy to create something like this:    
+  </p>
+  <source>/**
+ * Creates a reader capable of handling BOMs.
+ */
+public InputStreamReader newReader(final InputStream inputStream) {
+    return new InputStreamReader(new BOMInputStream(inputStream), StandardCharsets.UTF_8);
 }</source>
 </section>
 <section name="Printing with headers">