update underscore libs docs
update underscore libs docs


Former-commit-id: 50e7c279f8121f3839a7b2ba14230c0408cd9e10 [formerly c11bd2f51a2f718a794a75edfaef292c927d7291]
Former-commit-id: 55a85c145ff2128d0768a7cdf41b40deaba0b5db
andrewplummer/Sugar,andrewplummer/Sugar,romancow/Sugar,romancow/Sugar