Bundled version on GitHub pages

If someone wants a pre-bundled version that you can easily [try in your browser](https://mk-pmb.github.io/rosetta-js/tryit.html), I made one in [my gh-pages branch](https://github.com/mk-pmb/rosetta-js/tree/gh-pages).

Review the linked gh-pages branch and its tryit.html example to understand the existing pre-bundled version. Compare that setup with this repository's current build and hosting configuration, then verify that a bundled browser version is available on GitHub Pages and can be tried through the linked page.

Written by the indexing model from the issue text.