Bump Roxygen to v8.1.0

Change-Id: I9a1f2d53176dba7e28e8d5db1fbfa05d6551d1f3
diff --git a/man/revealjs_presentation.Rd b/man/revealjs_presentation.Rd
index 5d2e5d5..0d291c2 100644
--- a/man/revealjs_presentation.Rd
+++ b/man/revealjs_presentation.Rd
@@ -14,8 +14,8 @@
   fig_height = 6,
   fig_retina = if (!fig_caption) 2,
   fig_caption = FALSE,
-  self_contained = TRUE,
-  theme = "simple",
+  self_contained = FALSE,
+  theme = "ids",
   transition = "convex",
   background_transition = "fade",
   reveal_options = NULL,
@@ -69,7 +69,7 @@
 or just the body of a LaTeX document (\code{FALSE}). Note the LaTeX
 document is an intermediate file unless \code{keep_tex = TRUE}.}
 
-\item{theme}{Visual theme ("simple", "dark", "black", "sky", "beige", "serif", "solarized", "blood", "moon", "night", "league", or "white")}
+\item{theme}{Visual theme ("ids", "simple", "dark", "black", "sky", "beige", "serif", "solarized", "blood", "moon", "night", "league", or "white")}
 
 \item{transition}{Slide transition (
 "convex", "fade", "slide", "concave", "zoom", or "none"
@@ -125,7 +125,7 @@
 
 \item{lib_dir}{Directory to copy dependent HTML libraries (e.g. jquery,
 bootstrap, etc.) into. By default this will be the name of the document with
-\code{_files} appended to it.}
+\verb{_files} appended to it.}
 
 \item{pandoc_args}{Additional command line options to pass to pandoc}
 
@@ -213,7 +213,7 @@
 
 Version  is
 currently used and documentation for configurations can be found at
-\href{https://github.com/rajgoel/reveal.js-plugins/tree/4.1.5/4.1.5/chalkboard}{rajgoel/reveal.js-plugins}
+\href{https://github.com/rajgoel/reveal.js-plugins/tree/4.2.5/4.1.5/chalkboard}{rajgoel/reveal.js-plugins}
 
 By default, chalkboard and annotations modes will be accessible using keyboard
 shortcuts, respectively, pressing B, or pressing C.