Created intro text of the Twig Reference
Added functions section
Added filter section
Created tags section
Added 'almost core' bundles
Added missing dot in property path assembly.
Adding link to how to render templates
Adding link to @ParamConverter
Changed uses of we in security cookbooks
Removed space around dot operator.
Fix typo
Created introduction and toctrees
Created DialogHelper documentation
[WIP] FormatterHelper docs
Minor grammar tweak in service container documentation
Correcting method names in config component example
[#1868] Backporting details about getting Request Accept data to 2.0
[YAML] minor fix (loader => yml)
Added clarification on routes ending in optional params
Fixing indentation