PDFBOX-5660: improve javadoc, as suggested by Valery Bokov; closes #335

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1929808 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/main/java/org/apache/pdfbox/pdmodel/graphics/image/PNGConverter.java

@@ -54,8 +54,8 @@
  * If this is for any reason not possible, the factory will return null. You
  * must then encode the image by loading it and using the LosslessFactory.
  * <p>
- * The W3C PNG spec was used to implement this class:
- * https://www.w3.org/TR/2003/REC-PNG-20031110
+ * <a href="https://www.w3.org/TR/2003/REC-PNG-20031110">The W3C PNG spec</a> was used to implement
+ * this class.
  *
  * @author Emmeran Seehuber
  */
@@ -553,7 +553,8 @@ public int read(byte[] b, int off, int len) throws IOException
 
     /**
      * Map the renderIntent int to a PDF render intent. See also
-     * https://www.w3.org/TR/2003/REC-PNG-20031110/#11sRGB
+     * <a href="https://www.w3.org/TR/2003/REC-PNG-20031110/#11sRGB">sRGB Standard RGB colour
+     * space</a>.
      *
      * @param renderIntent the PNG render intent
      * @return the matching PDF Render Intent or null