HTML errors in HTMLBook spec

[MurakamiShinyu]

Validating the HTMLBook spec http://validator.w3.org/check?uri=http%3A%2F%2Foreillymedia.github.io%2FHTMLBook%2F shows some problems:

• Error Line 606, Column 40: Element pre not allowed as child of element ul in this context.

I think this pre element should be inside li element.

• Warning Line 674, Column 5: Consider using the h1 element as a top-level heading only (all h1 elements are treated as top-level headings by many screen readers and other tools).

      <section data-type="sect1" id="header_block">
    <h1>Header</h1>

I think this should be sect2 and h2.

I found some other minor problems:

• Bad markup of namespace URIs of MathML and SVG in Block Elements section

<p><code>&lt;math&gt;</code> (In MathML vocabulary; must be namespaced under
<a href="http://www.w3.org/1998/Math/MathML)">http://www.w3.org/1998/Math/MathML)</a></p>
...
<p><code>&lt;svg&gt;</code> (In SVG vocabulary; must be namespaced under
<a href="http://www.w3.org/2000/svg)">http://www.w3.org/2000/svg)</a></p>

I think this should be:

<p><code>&lt;math&gt;</code> (In MathML vocabulary; must be namespaced under
<code>http://www.w3.org/1998/Math/MathML</code>)</p>
...
<p><code>&lt;svg&gt;</code> (In SVG vocabulary; must be namespaced under
<code>http://www.w3.org/2000/svg</code>)</p>

• Doubled closing paren "))" in Notes in Footnote, endnote.

[sandersk]

Thank you very much @MurakamiShinyu. Fixes are now deployed.