Sphinx internal page redirects need to be added to README if PR accepted.

[jkwmoore]

See: https://github.com/rcgsheffield/sheffield_hpc/pull/2053

If this is merged, this methodology must be documented in the README.

The tl;dr of how / why this works is: "We get Sphinx to add static HTML files verbatim (within which we manually specify the correct HTML redirect) in the correct directory location to add a redirect which is not added to the TOCTree to avoid confusing the contents."