[Validation] Fix #1052 Documentation of unique()
[Validation] Fix #1052 Documentation of unique()

The documentation of BF_Form_validation.unique()'s parameters did not
match the use of those parameter by Bonfire's modules (specifically the
users and roles modules).

Additionally, though the table name was extracted from the second
parameter, it was not being used.

PeterRock/Ci-Bonfire3,PeterRock/Ci-Bonfire3,kelaskakap/cms-api-unggun,PeterRock/Ci-Bonfire3,kelaskakap/cms-api-unggun,kelaskakap/cms-api-unggun