bug#73475: Documentation for minify-build-system out of date

[Konrad Hinsen]

Hello everyone,

While trying to figure out how to use the minify-build-system,
I consulted the manual, compared it with the code, and concluded
that the manual is probably out of date.

It says:

   It adds @code{uglify-js} to the set of inputs and uses
   ...

The code used esbuild rather than uglify-js. Maybe there is more that
needs to be updated.

Cheers,
  Konrad.