Add index entries

I added an index part to the admin guide book and have started creating indexterm entries like the following. These need to be added throughout the book.

<preface id="About_JBoss"><title>About JBoss</title>
<para>
<indexterm><primary>JBoss</primary><secondary>about</secondary></indexterm>
<indexterm><primary>JBoss</primary><secondary>relation to Red Hat</secondary></indexterm>
JBoss, a division of Red Hat, is the global leader in open source middleware software, ...
</para>
<para>
<indexterm><primary>JBoss</primary><secondary>and Professional Open Source</secondary></indexterm>
<indexterm><primary>Professional Open Source</primary><secondary>JBoss</secondary>
</indexterm>
...