[docs] add shiny.router on DESCRIPTION

[jhk0530]

Hi, thanks for nice and SUPER COOL package.

I'm trying to create a shiny app with this. from runExample

it seems this requires shiny.router package to run demo shiny apps.

so What if we added it to the DESCRIPTION file in package?

Thanks !

[jhk0530]

What I tried is
examples/dashboard/app.R and it requires these packages

library(shiny.fluent)
library(shiny.router)
library(sass)
library(stringi)
library(purrr)