update script concat recommendation for HTTP/2

[balupton]

• In HTTP/1 multiple requests are slow as they block on the TCP level, as such, in HTTP/1 concatenation is better, as it eliminates the performance benefit of having a single request eliminating the blocking risk
• In HTTP/2 multiple requests occur in parallel on the TCP level, as such eliminating the need of the HTTP/1 concatenation practice while offering similar performance
• Using multiple requests increases the likelihood of a request being bundled, especially if the resource is popular, especially in the cases of CDN usage - whereas concatenation eliminates this benefit, as parts of the bundle cannot be cached as only the whole bundle can be
• As HTTP/2 multiple requests offers the same benefits of HTTP/1 single requests (concatenation) but as multiple requests increases chances of caching, then using multiple requests with HTTP/2 offers better performance over HTTP/1 concatenation practices

[jsf-clabot]

All committers have signed the CLA.

[icambron]

I think it would be simpler if we just remove the advice altogether. Moment's docs don't need to be a repository of best practices for HTTP. Closing in favor of #403