code: public void copyDocFiles(PackageElement pe) throws DocFileIOException {
          Location sourceLoc = getLocationForPackage(pe);
          copyDirectory(sourceLoc, DocPath.forPackage(pe).resolve(DocPaths.DOC_FILES));
      }
docs: Copy doc-files directory and its contents from the source
  package directory to the generated documentation directory.
  For example, given a package java.lang, this method will copy
  the doc-files directory, found in the package directory to the
  generated documentation hierarchy.
  
  @param pe the package containing the doc files to be copied
  @throws DocFileIOException if there is a problem while copying
  the documentation files