What part of "full-time" do you not understand?
Those words were in the tweet headline.
Whether she tries to come back eventually is moot. That loss shook her. She went on a pity tour of the talkshow circuit for many months after. Her leaving the octagon for the fake and theatrical ring is just a culmination of a lack of fortitude necessary for a comeback in the sport she's spent most of her life training for . Under contract means that her MMA career is over for the foreseeable future. Maybe for good.
"She can come back like Lesnar' hinges on hope or chance, not fact. Fact: she's now under contract with WWE which means she's out of the octagon for the foreseeable future.