[sudo-workers] Patch for sudoers manpage: wrong section for sudo_plugin manpage

[Todd C. Miller]

In message <9B56A0DB74E164469FE0F25F4B1E9E6C025A4CB683 at alvxmbw05.prod.quest.cor
p>
	so spake Ted Percival (Ted.Percival):

> The sudoers manpage says to check sudo_plugin(5) for documentation
> on plugins, but it's actually in section 8 (sudo_plugin(8)). Patch
> attached to correct the reference in sudo_plugin(5) manpage.

Fixed, thanks.  I don't think section 8 is really appropriate for
the plugin docs either, perhaps it should go in section 3.

 - todd