make clean doesn't remove html/.html…

[coke]

…Ideally, we shouldn't even be creating this file, but since we are, clean it up.

BTW, the title is

  <title>Disambiguation for &#39;&#39;</title>

[coke]

in

doc/Language/5to6-nutshell.pod6

the line

=head3 X<C<constant>|constant>

is the first thing that causes an empty .html to be generated.

And it's this block of code from htmlify that extracts the empty name:

when :("", Pod::FormattingCode $, "") {

[JJ]

Why does it happen that way? Maybe because of the C?