Add TOC element for SDFs. Fix calref#675

doc/editor/Advanced.html

@@ -26,7 +26,7 @@ <h2>Counting and Coordinates</h2>
 town is town 1, and so on. The coordinate system for Blades of Exile towns and dungeons
 starts with X = 0, Y = 0 (also written (0,0) ) in the upper left.</p>
 
-<h2>Stuff Done Flags</h2>
+<h2 id="sdfs">Stuff Done Flags</h2>
 
 <p>The single most important concept to master in scenario design is the Stuff Done Flag.
 The Stuff Done Flags are numbers the game keeps track of, which are used by the game to

doc/editor/Contents.html

@@ -43,6 +43,9 @@ <h2>Table of Contents</h2>
 <li><a href='Monsters.html'>Editing Monster Types</a></li>
 <li><a href='Items.html'>Editing Items</a></li>
 <li><a href='Advanced.html'>Advanced Topics Introduction</a></li>
+<ul>
+<li><a href='Advanced.html#sdfs'>Stuff Done Flags</a></li>
+</ul>
 <li><a href='Specials.html'>Special Encounters</a></li>
 <ul>
 <li><a href='Specials.html#intro'>Special Nodes</a></li>