broken link in bpf/bpf_devel_QA

[Ross Zwisler <zwisler@google.com>]

Hi,

I was checking out this page:

https://docs.kernel.org/bpf/bpf_devel_QA.html

and noticed that we have two links to .rst pages that are getting converted to
links in different ways.  This one:

  See the kernels selftest `Documentation/dev-tools/kselftest.rst`_
  document for further documentation.

is getting converted to a full external link:

  <p>See the kernels selftest <a class="reference external"
  href="https://www.kernel.org/doc/html/latest/dev-tools/kselftest.html">Documentation/dev-tools/kselftest.rst</a>
  document for further documentation.</p>

While this one:

  Finally to ensure support for latest BPF Type Format features -
  discussed in `Documentation/bpf/btf.rst`_

Is left as a short local link to a nonexistent .rst page:

  <p>Finally to ensure support for latest BPF Type Format features - discussed
  in <a class="reference external"
  href="btf.rst">Documentation/bpf/btf.rst</a> 

I think this could point to either of these locations and be okay:

https://www.kernel.org/doc/html/latest/bpf/btf.html
https://docs.kernel.org/bpf/btf.html

but, as it is it's showing up as a broken link.

Given that the page source for these two links are basically the same:

 `Documentation/dev-tools/kselftest.rst`
 and
 `Documentation/bpf/btf.rst`

I'm guessing this is an issue with how Sphinx is generating the resulting
html, probably because it's trying to generate a more 'local' sort link for
the btf.rst page?

Thanks,
- Ross