A couple of quick notes. You can sharpen the regex in html_files():

sub html_files {
    push @data, $File::Find::name if /\.s?html?$/i;
}
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I'd pass in $File::Find::name as a parameter just to encapsulate things further. merlyn might point out that using $ as an anchor will break if there's a newline at the end of the filename, but that shouldn't be a problem. (\z is safer.) Finally, I don't know why you have m?, but using /i makes it the regex case-insensitive. Saves time.

I'd also get rid of $temp in fileRead(). Always bugs me. :)