Add note about default encoding change to XML.save method documentation.

Author: Rogach

src/main/scala/scala/xml/XML.scala

@@ -74,6 +74,10 @@ object XML extends XMLLoader[Elem] {
    * Saves a node to a file with given filename using given encoding
    *  optionally with xmldecl and doctype declaration.
    *
+   *  Note: default encoding was ISO-8859-1 (latin1) in pre-1.0.7 scala-xml versions.
+   *  If your code depends on charaters in non-ASCII latin1 range, specify
+   *  ISO-8859-1 encoding explicitly.
+   *
    *  @param filename the filename
    *  @param node     the xml node we want to write
    *  @param enc      encoding to use