Preserve URLs for historical content

Google search shows about 444 000 000 links to the boost website, most of them likely to be to the documentation pages.

Please, make sure that these links stay valid after the update, and the "Internet amnesia" does not happen.

The W3C has a guide on how this can be achieved: https://www.w3.org/Provider/Style/URI , although probably a lot of time has passed since, and perhaps there are better guides available.