Corrected the patches subdirectory, though these are patches for older versions than in the current release.

Added build instructions for more PRACE machines, corrected a link that has changed since the last review.

Deleted examples on a CentOS 8 cluster for configurations that are no longer supported by the benchmark.

Update to the build instructions, with a further example, and a patch to avoid crashes during the tests with certain compilers (essentially a backport of 19.8.1 code to 1.5.2)