Update cookbook/security/acl.rst

See https://github.com/doctrine/DoctrineMongoDBBundle/pull/4#issuecomment-8428994
Fixed formatting
add contributing file in the root dir
Adding an overview of how the service container concepts fit togther
Fixing some errors in di workflow page
Add a cookbook entry to explain how to clear the cache before tests
Adding link to using annotations from routing book page
Fixing line length to avoid horizontal scrolling in DI component
Fixing CS in tags example
Adding line break in Routing tip
fixed casing in a method call
Changing some uses of we to you to be in keeping with the usual style
Add a chapter about node type in the config component
Moving sidebar below introduction of related command
Adding php to front of console command examples for consistency
Merge pull request #1697 from DenisGorbachev/patch-2

Update cookbook/security/acl.rst
[acl] Updating language to be more clear about requirements for Doctrine and ACL
Fix bad function name in console testing
Fixing bash coding block
Added a note about oneToMany relationships

Added a note about the oneToMany relationships in the Reversed
Engineering section of the doctrine cookbook