added support for sect4 (just converts to passthrough)

[adamwitwer]

Nice. Thanks, Sarah!

[sandersk]

This looks great, Sarah. Do you want to add in the same handling for sect5 while you're at it--e.g., do this:

<xsl:template match="sect4|sect5">
...

If you go ahead and make that change and resubmit the pull request, I'll go ahead and merge in.

Thanks again, Sanders