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.

2012/blakely/index.html

@@ -453,7 +453,8 @@ operation, then the results are undefined.</p>
 <p>For test-runs, use a resolution of 32. For simple expressions, the
 <a href="https://en.wikipedia.org/wiki/GIF">GIF</a> generation should take only
 a few seconds with a modern processor and full optimization. Runtime scales as
-<a href="https://en.wikipedia.org/wiki/Big_O_notation">O(N^3)</a> with resolution <code>N</code>,
+O<sup>(N</sup>3), (see <a href="https://en.wikipedia.org/wiki/Big_O_notation">Big O notation</a> web page)
+with resolution <code>N</code>,
 and more complex expressions take longer to compute. For example, increasing the
 resolution of <code>ripple.gif</code>
 to 250 took ~35 minutes to render on an <a href="https://en.wikipedia.org/wiki/Intel_Core#Core_i7">i7