Brian Steinberg Senior TV EditorBrian Williams didn’t go gentle into that good night.In a noticeable break from the journalistic demeanor he has projected for nearly three decades at NBC News and MSNBC, the veteran anchor used the final minutes of his tenure on MSNBC’s “11th Hour” to warn viewers of the frailty of American democracy and urged them to keep it safe — if they could.“My biggest worry is for my country. I’m not a liberal or a conservative.