use 'run' instead of 'exec'

[rlzijdeman]

Hi, using node v23.3.0 and and npm v10.9.0 on a Mac (M1) I was trying to configure my own ldwizard variant.

In step 3 and 6 I think the term 'exec' needs to be replaced by 'run'. Using exec does not execute anything.
If you agree, I'll update the docs and send a pull request.