fix alignment and HTML bug

Fixed the alignment of an arrow in `markdown.md`.

Fixed an HTML error, caught by `make quick_www`, in `bin/README.md`.

markdown.html

@@ -436,7 +436,7 @@ for the given page URL.</p>
 <h2 id="please-do-not-use-unindented-code-blocks">Please do NOT use unindented code blocks</h2>
 <p>Please do <strong>NOT</strong> start code blocks at the left-hand edge.</p>
 <pre><code>```
-This code block is NOT indented                   &lt;=== no thank you
+This code block is NOT indented                                 &lt;=== no thank you
 ```</code></pre>
 <p>We request that you indent the code block by 4 spaces:</p>
 <pre><code>```