Remove stale example.

Fixes cakephp/cakephp#3892
Added info about blowfish hash generation removal from Security::hash().
Merge pull request #1463 from ADmad/3.0

Added info about blowfish hash generation removal from Security::hash().
Update authentication page to correctly reflect changes in 3.0.
Fix grammar.
Merge pull request #1464 from ADmad/3.0-auth

Update authentication page to correctly reflect changes in 3.0.
Update themes.rst

Corrected a typo
Merge pull request #1465 from sanisoft/3.0

Update themes.rst
Add a few examples of `use` for Router

Refs cakephp/cakephp#3909
Update docs for Router::parseExtensions()

Refs cakephp/cakephp#3905
Reorganize the options docs and add validator option.

Refs cakephp/cakephp#3918
Remove reference to old 0/1/2 debug configuration

Description of `debug` Config parameter still referred to 2.x 0/1/2 style, not new 3.x true/false style.
Merge pull request #1472 from robojamison/patch-1

Remove reference to old 0/1/2 debug configuration
update docs around connection manager deprecations
Update cakephp-folder-structure.rst
Merge pull request #1474 from glorand/patch-1

Update cakephp-folder-structure.rst
Merge pull request #1473 from dereuromark/3.0-depr

update docs around connection manager deprecations
Merge pull request #1471 from cakephp/3.0-form-context

Reorganize the options docs and add validator option.
Add info about $confirmMessage arg removal.
Merge pull request #1476 from ADmad/3.0-helper

Add info about $confirmMessage arg removal.