Process improvements are not chased to completion

[rptb1]

We do not have a complete process to ensure that process improvements resulting from review (or elsewhere) are completed and deployed. We're relying too much on memory and individual diligence.

We should ensure they don't get lost with written procedure.

Raised from https://github.com/Ravenbrook/mps/blob/654c24c4eccec4716478165a252fe51f07e5afdb/procedure/review.rst#L1120-L1123

[thejayps]

Process improvements are taking place (hence not critical to fix). We just arent' systematically tracking down and actioning everything previously identified

[thejayps]

Comment from @rptb1: If someone want's to fork the project, they won't necessarily have a culture around process improvement, they will need a hook to do it.