Move Security content to the Advanced Administration Handbook

[javiercasares]

We should move some content to the Security folder in the Advanced Administration handbook.

• [ ] The first part of the page, to the Security (index) part.
• [ ] The Throttling Multiple Login Attempts to the Brute Force Attacks page.
• [ ] The File System to the Changing File Permissions page
• [ ] The WordPress Users and Roles to a new page?
• [ ] The HTTPS and TLS to the HTTPS page
• [ ] The Caching Security to a new page inside Security?
• [ ] The Responsible Disclosure to the main page of the Security page.