replace old ASCII > style with markdown code blocks

1992/adrian/README.md

@@ -257,7 +257,9 @@ many seconds.
 If either `adbasename` or `adsleep` is invoked with too few parameters,
 the program will print the error message:
 
-> Segmentation fault (core dumped)
+```
+    Segmentation fault (core dumped)
+```
 
 (The exact text of the above error messages varies from machine to
 machine.)  The four programs which read from stdin require lines

1992/adrian/index.html

@@ -286,9 +286,7 @@ command. Invoke with a single integer parameter, and it will pause for that
 many seconds.</p>
 <p>If either <code>adbasename</code> or <code>adsleep</code> is invoked with too few parameters,
 the program will print the error message:</p>
-<blockquote>
-<p>Segmentation fault (core dumped)</p>
-</blockquote>
+<pre><code>    Segmentation fault (core dumped)</code></pre>
 <p>(The exact text of the above error messages varies from machine to
 machine.) The four programs which read from stdin require lines
 shorter than 999 characters.</p>