fix more broken markdown links

Fixed stuff we broke by mistake, previously.

Ran `make www` to perform the above.

TODO: Fix stuff we broke by mistake doing the above.

TODO: Fix more broken markdown links.

2020/ferguson1/HACKING.html

@@ -742,7 +742,7 @@ snakeskin would be the same size the snake was and the snake would grow as it
 slithered out. But that would fill the screen very quickly of course. Maybe the
 snakeskin has some other purpose?</p>
 <h2 id="snake-moves-faster-over-time">Snake moves faster over time</h2>
-<p>In the game [Surround](https://en.wikipedia.org/wiki/Surround_(video_game) you
+<p>In the game <a href="https://en.wikipedia.org/wiki/Surround_(video_game)">Surround</a> you
 have no control over the speed. I believe there are five different speed levels
 but the player has no control over it except the drawing mode. It would be
 possible to make it so the snake moves faster over time. How often and by what