Affects Version/s: None
Fix Version/s: 2.5
Security Level: All
This issue is created automatically through a Github pull request on behalf of naitsirch:
I have provided an example of YAML mapping for unique constraints which is equivalent to the [annotation reference for unique constraints](http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/reference/annotations-reference.html#annref-uniqueconstraint).
It is really basic, but I think better than nothing. Because there are severall people who search for that.
I felt the need of that doc, too