You can define the variable PRE_BODY_CLOSE to add text just
before the HTML </body> element. Nothing is added by default.
If PROGRAM_NAME_IN_FOOTER is set, the date and name of the
program that generated the output are output in the footer.
By default, the JavaScript license web labels page is formatted and output at the end of file (see JavaScript Interface and Licenses in Texinfo).
The format_end_file function reference give full control over the page
footer formatting done at the bottom of each HTML output file.
$file_end format_end_file ($converter, $filename, \%output_unit) ¶$filename is the name of the file output.
\%output_unit is the last output unit of the file.
This function should print the page footer, including
the </body> element.