add back TASK_LOST_WHILE_DOWN for compatibility

Fixes #256
should have no associated task state.
UI docs rewrite
Tiny aesthetic change
Added TL;DR
Remove $s for easier copy-pasting
Merge pull request #259 from HubSpot/improved-ui-docs

New SUI docs
Merge pull request #3 from HubSpot/master

Merge from Hubspot