Add build step with "Bookmarkleter"

[irae]

On future versions of the emulator, might be interesting to use "bookmarkleter" to create actual bookmark, that won't require a CDN.

By automating it, after any stable patch, one could run npm run build and get the bookmarklet generated and updated on Readme.md file.

https://github.com/chriszarate/bookmarkleter

I am out of time as of now, but maybe I will create a pull request for that later. Leaving the suggestion here anyway, as the maintainers might like the idea even before I get to it.