Missing demo code - userMessages

[schloerke]

Similar to #52

The CRAN versions of this application is missing in shinydashboardPlus

outstanding-shiny-ui/shiny-custom-handler.Rmd

Lines 1002 to 1007 in 525d2bc

	```{r, eval=FALSE}
	shinyAppDir(system.file(
	"vignettes-demos/userMessages",
	package = "shinydashboardPlus"
	))
	```

I could not easily fix the code.

[DivadNojnarg]

Now that shinydashboardPlus 2.0.2 is on CRAN, I close the issue. I'll have to recompile the book with the good package reference.