Define and document HLT2 line authoring guidelines

It is useful for HLT2 line authors to work against some requirements when writing their lines:

1. What rate should my line take?
2. How much bandwidth should my line use?
   • Should my line be a Turbo line? How can I choose?
3. What's a 'reasonable' amount of time for my line to take?
   • Perhaps more useful at the moment: how many combinations are reasonable, what number of vertex fits?
4. If my line isn't going to be a Turbo line, can I wait to write it until next year, when the sprucing will be run?

We should address these questions in the authoring document.