Add docbook2xhtml-single-notoc.xsl file.
    
    - This file is used to produce html release notes, eula and the index
      file set as default page for web browsers inside the distribution.
      None of these files use style sheets, nor images and table of
      contents.  They provide the simplest document possible to build
      using asciidoc as source documentation format. There is no need to
      produce a plain text version for these files, asciidoc files are
      already plain text files. Use them.