Lazy `parameter {}` docs: computed first time "used" -> "declared"

[BenWoodworth]

Behavior has changed since these docs were written, so it's no longer accurate.

Change:

Declares a parameter with the given lazyArguments. The arguments are only computed the first time the parameter is used, and not at all if used declared.
This parameter function is useful to avoid computing the arguments every iteration. Instead, these arguments will only be computed the first time the parameter is used as needed.