Refactor book indexes

[weaverryan]

All of the indexes in the book need to be checked and updated.

[weaverryan]

This is still valid - there should be at least an index at the top of every entry, and then we should go check the generated index and make sure it's consistent - terms are spelled the same everywhere so that they group properly, etc.

[richardmiller-zz]

@weaverryan is there anything still to be done with this?

[weaverryan]

I've just pushed another small commit for this, but it looks like you've already done most of the cleaning up here :)

Closing this