VFS related tuning docs

The following VFS_Tuning sub-section from the JBAS_Tuning section in
https://svn.jboss.org/repos/jbossas/projects/docs/community/5/Administration_And_Configuration_Guide/en-US/Performance_Tuning.xml

needs input.

<section id="JBAS_Tuning">
<title>Tuning JBoss Application Server</title>
...
<section id="VFS_Tuning">
<title>VFS Tuning</title>
<section>
<title>VFS Cache Tuning</title>
<para>Magic about the caching settings...</para>
</section>
<section>
<title>Annotation Scaning Tuning</title>
<para>Magic about controlling annotations scaning...</para>
</section>
</section>
</section>