[xml/sgml-pkgs] Bug#746929: mention that --htmlout oddly puts surrounding tags on STDERR instead of STDOUT

[積丹尼 Dan Jacobson]

Package: libxml2-utils
Version: 2.9.1+dfsg1-3
Severity: wishlist
File: /usr/share/man/man1/xmllint.1.gz

Mention that

       --htmlout
           Output results as an HTML file. This causes xmllint to output the
           necessary HTML tags surrounding the result tree output so the
           results can be displayed/viewed in a browser.

oddly puts those surrounding items on STDERR instead of STDOUT.