Add missing variable in templates regarding toc (#127)

Related to #123 and alignement with `html_document()` behavior
diff --git a/man/revealjs_presentation.Rd b/man/revealjs_presentation.Rd
index e89753d..4aed888 100644
--- a/man/revealjs_presentation.Rd
+++ b/man/revealjs_presentation.Rd
@@ -8,6 +8,8 @@
   incremental = FALSE,
   center = FALSE,
   slide_level = 2,
+  toc = FALSE,
+  toc_depth = 3,
   fig_width = 8,
   fig_height = 6,
   fig_retina = if (!fig_caption) 2,
@@ -45,6 +47,11 @@
 building vertically. It is not recommended that you use deeper nesting of
 section levels with reveal.js.}
 
+\item{toc}{\code{TRUE} to include a table of contents in the output (only
+level 1 headers will be included in the table of contents).}
+
+\item{toc_depth}{Depth of headers to include in table of contents}
+
 \item{fig_width}{Default width (in inches) for figures}
 
 \item{fig_height}{Default height (in inches) for figures}