Added cookbook page about sessions directory.
Add some clarification to Quick Tour Working with Environments

Also, for the session token: identify what the "weird" hex number is, and and replace "weird" with "long" (a more apt description).
The instructions are incomplete.

Added routes and doctrine commands
removed duplicate timestamp limitation notice
added timestamp limitation notice for datetime
Merge pull request #2674 from jbafford/i2672

Add some clarification to Quick Tour Working with Environments
Added note about setting the label to false
Updated doc for the new way to render partials
Removed trailing whitespace
Deleted blank lines
Made sentence more clear
Add PDO error handling details
Added namespace declaration to MainController.php.
Changed </components/yaml/introduction> to </components/yaml/format> per PR feedback.
[Validation] fixed a link
Fixed wrong used class
fix group sequence order
remove unmaintained translations
Added missing class to static callback example in PHP

Signed-off-by: Pedro Junior <v.ju.ni.or.v@gmail.com>
Documented synthetic services