DOCUMENTARY PREMIERE: This two-part documentary (part two is televised tonight immediately after part one, so Elvis won’t leave the building) tackles a tough challenge: After all these years and all these nonfiction documentaries and fact-based dramas, what else is left to say, or to learn, about Elvis Presley? I asked that question of the writer of an Elvis docudrama about 20 years ago, and I’ll never forget his answer: Elvis had a terrible time remembering names, so he called every