The wiki page on ES6-8 support could use some updates for FW v5.8

[moloko]

https://github.com/adaptlearning/adapt_framework/wiki/Adapt-v5.3-%E2%86%92-the-one-with-ES6-to-8-support

As, with the release of v5.8.0, we've switched from requirejs to rollup, it would be good to update the above Wiki page (or add another if that's more appropriate) to reflect the change in bundler.