Use simpler location blocks

there's no need for a regex match for the url `/index.html`

Use prefix-matching for assets as that's the nginx-way® and the rule is simpler.

Note that this isn't the case on istlsfastyet.com:

> make sure you are using cache busting filenames or query params
If you know what you're doing, you can definitely optimize it and scope it to particular directories. The problem is, most people will just copy/paste the snippets and never think about it twice (and then we are left wondering why gzip and caching is not applied to so many resources). Let's keep the generic snippet here.