section in User's Guide on moving transformed parameters to local variables #943

Respondent "Somebody" on @andrewgelman's blog suggested adding a section to the efficiency chapter of the User's Guide to talk about moving transformed parameters to local variables. Here's the request:

https://statmodeling.stat.columbia.edu/2026/05/04/expanding-the-stan-users-guide/#comment-2414300

This can be a very short section. We also want to emphasize that many things can be recovered later, including any necessary generated quantities.