Slightly modify the function documentation details

The intention I had when I wrote `ehpi::epi()` in the Rd is misunderstood by
either box::help or by the man page generation of plain text documentation which
box::help fetches. This should fix that.

Author: bryce-carson

R/epi.R

@@ -1,7 +1,7 @@
 #' An interface to eight compartmental epidemic models.
 #'
-#' [ehpi::epi()] is an application programming interface (for the
-#' Shiny application that motivated its creation) or a convenient function for
+#' ehpi is an application programming interface (for the Shiny application that
+#' motivated its creation) or a convenient function [ehpi::epi()] for
 #' interactive use in epidemic modelling. The arguments provided to the function
 #' determine compartments used in the model that is run.
 #'