Suggestion: /.well-known/llms.txt instead

These days there's a increasingly adopted alternative to the `/robots.txt` and `/sitemap.xml` and `/favicon.ico` standards - the `/.well-known` prefix: https://en.wikipedia.org/wiki/Well-known_URI

These have been registered with IANA since ~2010: https://www.iana.org/assignments/well-known-uris/well-known-uris.xhtml

The RFC has the argument for why this is a good idea, which honestly I haven't read in a few years so I'm a bit rusty on: https://datatracker.ietf.org/doc/html/rfc5785

Oh, maybe this is it (quoting the RFC):

> When this happens, it is common to designate a "well-known location" for such data, so that it can be easily located. However, this approach has the drawback of risking collisions, both with other such designated "well-known locations" and with pre-existing resources.
>
> To address this, this memo defines a path prefix in HTTP(S) URIs for these "well-known locations", "/.well-known/". Future specifications that need to define a resource for such site-wide metadata can register their use to avoid collisions and minimise impingement upon sites' URI space.

Start by reading RFC 5785 and the IANA well-known URIs registry linked in the issue, then compare the proposed /.well-known/llms.txt location with the existing /llms.txt convention described by the project. Done means the project has a resolved decision on whether and how this alternative should be supported.

Written by the indexing model from the issue text.