TOC for Markdown should now work for both Pandoc < 2.0 and >= 2.0

The use of $toc$ and $table-of-contents$ flags changed, see:
https://pandoc.org/releases.html#pandoc-2.0-29-oct-2017
under "Behaviour changes"

bin/template.html

@@ -54,7 +54,13 @@ $endif$
 $endif$
 $if(toc)$
 <nav id="$idprefix$TOC">
+$if(table-of-contents)$
+  <!-- pandoc >= 2.0 -->
   $table-of-contents$
+$else$
+  <!-- pandoc < 2.0 -->
+  $toc$
+$endif$
 </nav>
 $endif$
 $body$

bin/update_html

@@ -93,18 +93,18 @@ function render_md_html {
   html="$2"
   relroot="$( dirname $md | sed -E 's/^.\///' | sed -E 's/[^/]+/../g' )"
 
-  # Look for `toc: true` in metadata (first ten lines of file)
+  # Look for `show-toc: true` in metadata (first ten lines of file)
-  if head -n 10 "$md" | grep --quiet 'toc: true' ; then
+  if head -n 10 "$md" | grep --quiet 'show-toc: true' ; then
-    toc='--table-of-contents'
+    tocflag='--table-of-contents'
   else
-    toc=''
+    tocflag=''
   fi
 
   pandoc \
     --from=markdown \
     --to=html5 \
     --standalone \
-    $toc \
+    $tocflag \
     --template="$template" \
     --variable="lang:en" \
     --variable="rel-root:$relroot" \

doc/gf-refman.md

@@ -2,7 +2,7 @@
 title: GF Language Reference Manual
 author: Aarne Ranta, Krasimir Angelov
 date: June 2014, GF 3.6
-toc: true
+show-toc: true
 ---
 
 This document is a reference manual to the GF programming language. GF,