Correction proposed to subsection headings of Appendix D

[jonathan]

The various vertical coordinates described by Appendix D of the CF standard should be titled as unnumbered subsections, not as examples. They were unnumbered subsections in the beta CF standard document, and the formatting was changed when the document was translated to docbook. There was a similar problem with Appendix F, which was corrected by ticket 18.

Jonathan

[mlaker1]

Fixed defect.