Add back JavaScript files to Doxygen-generated docs

[Xmader]

JavaScript is actually supported by Doxygen

In https://www.doxygen.nl/manual/config.html EXTENSION_MAPPING

... language is one of the parsers supported by doxygen: IDL, Java, JavaScript, Csharp (C#), C, C++, Lex, D, PHP, md (Markdown), Objective-C, Python, Slice, VHDL, Fortran

And I could verify it working by looking at the generated Class List page.

This reverts commit ea30c367c7ca5b5bee39905ad091275acff18354 "chore(docs): JavaScript is not support by Doxygen".

Actually I added JavaScript on purpose in commit c89a67fc50788799833f299362e3000df4822b84.