text: Title: Documentation in readme for allowed parameter values
  Body: It would be great to include the allowed parameter values in the GitHub read-me. When setting parameters for a production server I had to guess or search many of them in the Discourse forum for that kind of information.
  
  Example of questions that this documentation would avoid:
  
  - --api-keys is a flag. On the command line it's obvious. But when using LT_API_KEYS, is defining it enough? Should I put true?
  - Is LT_REQUIRE_API_KEY_ORIGIN a toggle, with the origin automatically detected? Or a string? I which case, can I put a wildcard there such as *.mydomain.com ?
  