Spring Security Remove empty Appendix Section from docs

Appendix Section in docs is empty it should be removed.

Comment From: rwinch

This is actually a mistake in the hierarchy. The following sections should be in the Appendix:

• Security Database Schema
• The Security Namespace
• Spring Security Dependencies
• Spring Security FAQ

Comment From: akohli96

@rwinch May I take on this one?

Comment From: jzheaux

It's yours, @akohli96, thanks for volunteering!