Add make.R

.Rbuildignore

 ^\.Rproj\.user$
 ^README\.Rmd$
 ^LICENSE\.md$
+^make\.R$

make.R

+setwd(here::here("vignettes"))
+message("Rendering vignettes/template-variables.Rmd for GitHub")
+rmarkdown::render("template-variables.Rmd", output_format = rmarkdown::github_document(), quiet = TRUE)
+unlink("template-variables.html")
+
+setwd(here::here())
+message("Rendering README.Rmd for GitHub")
+rmarkdown::render("README.Rmd", quiet = TRUE)
+unlink("README.html")