Add "S" prefix to model description labels

This only applies to the PDF output, intended for use as supplementary
materials to the main article.

vignettes/articles/model-description.Rmd

@@ -15,6 +15,10 @@ output:
     keep_tex: true
     highlight: haddock
     extra_dependencies: ["framed"]
+header-includes:
+  - "% Increase the ToC section number width to admit longer labels."
+  - \usepackage{tocloft}
+  - \cftsetindents{section}{0em}{2.5em}
 vignette: >
   %\VignetteIndexEntry{Model Description}
   %\VignetteEngine{knitr::rmarkdown}
@@ -66,6 +70,12 @@ pkgdown:
 \newcommand{\nto}{\nrightarrow}
 
 ```{=latex}
+% Add "S" prefix to pages, sections, tables, and figures.
+% See https://stackoverflow.com/a/50213009 for details.
+\renewcommand{\thepage}{S\arabic{page}}
+\renewcommand{\thesection}{S\arabic{section}}
+\renewcommand{\thetable}{S\arabic{table}}
+\renewcommand{\thefigure}{S\arabic{figure}}
 % Display code blocks with a light grey background and a border.
 \definecolor{shadecolor}{RGB}{247,247,247}
 \renewenvironment{Shaded}{%