Migrating to issue from PR comment

I think it'd be great to document what compressions are supported, although this is not entirely generalizable across pathogen repos in the way we're aiming for with the multiple_inputs so we have to be careful with how we write the comment. As I understand it, and assuming we use separate merge_sequences and merge_metadata rules, then the supported compressions are:

• Metadata
  • Multiple sources: whatever augur merge supports
  • Single source: what's supported by the rules where input_metadata is used (4 different rules for zika as it currently stands)
• Sequences
  • Multiple sources: whatever augur merge supports
  • Single source: what's supported by the rules where input_sequences is used (only one rule for zika as it currently stands)