Many parameters have placeholder documentation

E.g., in `?DelphiRF::DelphiRF`:
```
train_models-template: DESCRIPTION GOES HERE

make_predictions-template: DESCRIPTION GOES HERE

model_save_dir-template: DESCRIPTION GOES HERE

indicator-template: DESCRIPTION GOES HERE

lp_solver-template: DESCRIPTION GOES HERE

signal-template: DESCRIPTION GOES HERE

geo_level-template: DESCRIPTION GOES HERE

geo-template: DESCRIPTION GOES HERE

signal_suffix-template: DESCRIPTION GOES HERE

lambda-template: DESCRIPTION GOES HERE

gamma-template: DESCRIPTION GOES HERE

value_type-template: DESCRIPTION GOES HERE

training_end_date-template: DESCRIPTION GOES HERE

training_days-template: DESCRIPTION GOES HERE
```

It's possible that this is the result of something going wrong migrating to roxygen `@template`s; it looks like many/all of the template files [here](https://github.com/cmu-delphi/DelphiRF/tree/main/man-roxygen) have placeholder text, while the parameters that do not involve templates have working documentation.