Old installation docs

[Joseph Myers]

On Wed, 20 Oct 2021, Jonathan Wakely via Gcc wrote:

> https://gcc.gnu.org/install/ says:
> 
> "There are also some old installation instructions
> <https://gcc.gnu.org/install/old.html>, which are mostly obsolete but still
> contain some information which has not yet been merged into the main part
> of this manual."

Those should have been removed in GCC commit 
431d26e1dd18c1146d3d4dcd3b45a3b04f7f7d59, it seems that forgot to remove 
the link in the HTML version.

-- 
Joseph S. Myers
joseph@codesourcery.com