Merge branch 'x86' into docs-next

Merge the x86 docs conversion from Changbin Du, who writes:

> The kernel now uses Sphinx to generate intelligent and beautiful
> documentation from reStructuredText files. I converted all of the Linux
> x86 docs to rst format in this serias.
>
> For you to preview, please visit below url:
> http://www.bytemem.com:8080/kernel-doc/index.html
>
> Thank you!

The whole series was:

Acked-by: Ingo Molnar <mingo@kernel.org>