Label changes

[benjub]

Since labels in set.mm are sometimes modified, we need to keep the book up-to-date with theses changes. They can be found in the file https://github.com/metamath/set.mm/blob/develop/changes-set.txt

The latest one which appears in the book is: trud --> mptru

[avekens]

The latest one which appears in the book is: trud --> mptru

This is a very important issue, because with the theorem currently labeld with ~trud (formerly ~a1tru), the instruction how to convert a theorem in deduction form into a theorem in inference form (see section 3.9.3) is completely misleading. I added already a corresponding footnote in the German translation of the book. Maybe an example would be helpful here (e.g., ~hadbi123i or ~abeq2i) - although we would get additional hardcoded label names which might be changed, this would give at least more clues where to find additional material.

[digama0]

Can we mark all set.mm labels in the book with a TeX macro? That way we can scrape it in CI and double check that they all exist.

[avekens]

trud replaced by mptru in both tex-sources (original and German translation) and errata enhanced accordingly with PR #246.