RST implicit internal links to headers:
pandoc -f rst Years ----- Years_ ^D <h1 id="years">Years</h1> <p><a href="#years">Years</a></p>
pandoc -f rst Years_ Years ----- ^D <p><a href="#years">Years</a></p> <h1 id="years">Years</h1>
pandoc -f rst Years and years --------------- `Years and years`_ ^D <h1 id="years-and-years">Years and years</h1> <p><a href="#years-and-years">Years and years</a></p>
pandoc -f rst Years and *years* ----------------- `Years and years`_ ^D <h1 id="years-and-years">Years and <em>years</em></h1> <p><a href="#years-and-years">Years and years</a></p>