Move dispatch filters under routing in TOC.
Moved CSRF and Security component into a "Security" top level TOC item
Updated epub and pdf contents as outlined by @ADmad
Merge pull request #1844 from cakephp/toc

Move dispatch filters under routing in TOC.
[fr] follows #1844
Merge pull request #1846 from cakephp/3.0-security-top-level-toc-item

Moved CSRF and Security component into a "Security" top level TOC item
follow #1846
Fix missing heading in search index.
Fix heading on entities.

Having references before the heading caused the index building script to
fail.
Fix index build errors.

The title has to be the first line in the file for the indexing script
to work.
Add docs for cakephp/cakephp#4816