[Rd] Documentation bug (PR#7483)

[tac at nei.nih.gov]

Full_Name: Terry A. Cox
Version: 2.0.1
OS: Mac OS X
Submission from: (NULL) (138.88.250.18)


In the file, http://cran.r-project.org/doc/manuals/R-exts.html, several of the
headers have incorrect closing tags, e.g., 
 
 <h3 class="subsection">The <code>DESCRIPTION</code> file</h4>

This creates a problem in standards-compliant web browsers such as Safari.