R: Vignettes and other documentation

# Vignettes and other documentation

## Vignettes from package 'rgl'

rgl::WebGL |  | User Interaction in WebGL | HTML | source | R code
rgl::demos |  | rgl Demos | HTML | source | R code
rgl::deprecation |  | Deprecating the `rgl.*` interface | HTML | source | R code
rgl::pkgdown |  | Using RGL in pkgdown web sites | HTML | source | R code
rgl::rgl |  | rgl Overview | HTML | source | R code
rgl::transparency |  | A Note on Transparency | HTML | source | R code