Fix expect.extend example in docs (#2352)
Fix expect.extend example in docs (#2352)


cpojer/jest,ide/jest,facebook/jest,bookman25/jest,mpontus/jest,cpojer/jest,mpontus/jest,skovhus/jest,facebook/jest,ide/jest,bookman25/jest,skovhus/jest,bookman25/jest,cpojer/jest,mpontus/jest,facebook/jest,skovhus/jest,ide/jest