add epinow explainer

vignettes/estimate_infections_options.Rmd.orig

@@ -331,9 +331,15 @@ get_elapsed_time(non_parametric$fit)
 plot(non_parametric)
 ```
 
-# Running the model simultaneously on multiple regions
+# Running the model in production mode
 
-The package also contains functionality to conduct inference contemporaneously (if separately) on multiple time series, e.g. to run the model on multiple regions.
+The package contains functionality to run `estimate_infections` in production mode, i.e. with full logging and saving all relevant outputs to the hard drive.
+This is done with the `epinow()` function, that takes the same options as `estimate_infections` with some additional infections that determine, for example, where output gets stored and what output exactly.
+The function can be a useful option when, e.g., running the model daily with updated data on a high-perforumance computing server to feed into a dashboard.
+
+## Running the model simultaneously on multiple regions
+
+The package also contains functionality to conduct inference contemporaneously (if separately) in production mode on multiple time series, e.g. to run the model on multiple regions.
 This is done with the `regional_epinow()` function.
 
 Say, for example, we construct a data sets containing two regions, `testland` and `realland` (in this simple example both containing the same case data).