Added docs for validator that checks duplication in distinct intents
Added docs for validator that checks duplication in distinct intents

Signed-off-by: Vinicius Lima <c27b5905f1ba3362784f73a59db751acff0fd188@gmail.com>

RasaHQ/rasa_nlu,RasaHQ/rasa_nlu,RasaHQ/rasa_nlu