readme fixes

[sckott]

These packages contain README.md files with invalid HTML output created
by pandoc 1.12.4.2 according to W3C-validator.

I attach the HTML errors and warnings found below, and will put copies
of the corresponding HTML files up at
http://www.r-project.org/nosvn/pandoc.

Please investigate the problems and fix as needed.

Afaics, many of the problems are caused by adding "raw" HTML elements in
the README.md files and not realizing that the default output format
"html" is XHTML 1 (and not HTML 5). E.g., a raw
results in an

end tag for "br" omitted, but OMITTAG NO was specified

error.

Best
-k

rfisheries.html:
  Valid: FALSE (errors: 4, warnings: 0)
  Errors:
    line  col  message
      31   59  required attribute "alt" not specified
      35   76  required attribute "alt" not specified
     123   86  required attribute "alt" not specified
     152   98  required attribute "alt" not specified