Topic on setting HTTP priority of resource requests

When loading a page with many resources it can be useful to prioritize the requests so that the page appears to render more quickly. It would be useful to have a topic on this.

There are a bunch of ways to do this:

• Use fetch() and set the priority in Request.priority.
• Set the HTTP priority on HTMLLinkElement, HTMLIFrameElement, and HTMLImageElement elements (and associated tags) using the fetchpriority attribute.
• In future maybe Priority HTTP header. There are also some ideas (from here), some of which may be relevant (e.g. marking the non-critical ones as async):
• Mark non-critical scripts as async
• Consider inlining @font-face declarations directly into HTML
• Avoid using CSS background images or @import
• Use preload to retrieve critical resources earlier

Possible locations for such a page are under these:

• https://developer.mozilla.org/en-US/docs/Web/Performance
• https://developer.mozilla.org/en-US/docs/Web/API/fetch ?

This comes out of the discussion here: https://github.com/mdn/content/issues/14561