Clarify docs on default values
Clarify docs on default values

  - See https://github.com/mbryzek/apidoc/issues/626%23issuecomment-307346393

mbryzek/apidoc,gheine/apidoc,mbryzek/apidoc,gheine/apidoc,gheine/apidoc,apicollective/apibuilder,mbryzek/apidoc,apicollective/apibuilder,apicollective/apibuilder