add transcript view ('r') for text-to-speech read-aloud extensions
Read-aloud browser extensions cannot walk a reveal.js deck: slides
outside the current one are display:none and the visible page text is
indexed only once at page load, so such extensions stop after the title
slide. Pressing 'r' now toggles a transcript view -- a single scrollable
page containing every slide's content and speaker notes (overview TOC
lists excluded, fragments shown, rebuilt on every open) -- which
extensions can read from start to finish. Styled in the ids theme;
closes on click or Escape.
Change-Id: Ia3df9dfa68b9699d318d747831ac8a0e270c8271
diff --git a/R/revealjs_presentation.R b/R/revealjs_presentation.R
index dab04c7..e73ede9 100644
--- a/R/revealjs_presentation.R
+++ b/R/revealjs_presentation.R
@@ -40,6 +40,12 @@
#' useful for practicing a talk on a phone or tablet. It follows along as
#' you change slides and only appears if the deck contains notes at all.
#'
+#' Pressing `r` toggles a transcript view: a single scrollable page
+#' containing every slide's content and speaker notes. Text-to-speech
+#' ("read aloud") browser extensions cannot walk a reveal.js deck, since
+#' hidden slides are not part of the visible page text -- the transcript
+#' gives them something they can read from start to finish.
+#'
#' ## Slide timing
#'
#' Speaker time can be planned per slide and per speaker by adding a comment