Missing end-tag in the documentation guide

[Tommy Reynolds]

Uttered Christian Huegel <christian.huegel at redhatforum.net>, spake thus:

> The line:
> <xref linkend="ch-tutorial"><xref> and <xref 
> linkend="s1-tutorial-parent"></xref>

Well, actually, since the content model for <xref> is EMPTY, the
proper form should be:

	<xref linkend="foo" />

Cheers!