toc.yml

---
toc: true
...

typescript

$ pandoc -s -o - -t markdown x.yml 
---
x: True
...


$ pandoc -s -o - -t markdown toc.yml
---
toc: True
...

true


$ exit

version.txt

pandoc 1.16
Compiled with texmath 0.8.4.1, highlighting-kate 0.6.1.
Syntax highlighting is supported for the following languages:
    abc, actionscript, ada, agda, apache, asn1, asp, awk, bash, bibtex, boo, c,
    changelog, clojure, cmake, coffee, coldfusion, commonlisp, cpp, cs, css,
    curry, d, diff, djangotemplate, dockerfile, dot, doxygen, doxygenlua, dtd,
    eiffel, email, erlang, fasm, fortran, fsharp, gcc, glsl, gnuassembler, go,
    haskell, haxe, html, idris, ini, isocpp, java, javadoc, javascript, json,
    jsp, julia, kotlin, latex, lex, lilypond, literatecurry, literatehaskell,
    llvm, lua, m4, makefile, mandoc, markdown, mathematica, matlab, maxima,
    mediawiki, metafont, mips, modelines, modula2, modula3, monobasic, nasm,
    noweb, objectivec, objectivecpp, ocaml, octave, opencl, pascal, perl, php,
    pike, postscript, prolog, pure, python, r, relaxng, relaxngcompact, rest,
    rhtml, roff, ruby, rust, scala, scheme, sci, sed, sgml, sql, sqlmysql,
    sqlpostgresql, tcl, tcsh, texinfo, verilog, vhdl, xml, xorg, xslt, xul,
    yacc, yaml, zsh
Default user data directory: /Users/rbdixon/.pandoc
Copyright (C) 2006-2015 John MacFarlane
Web:  http://pandoc.org
This is free software; see the source for copying conditions.
There is no warranty, not even for merchantability or fitness
for a particular purpose.

x.yml

---
x: true
...