When a conduit method requires a string constant, call it "string-const" not "enum"
Summary: Ref T5058. The use of "enum" is confusing; we mean "choose one of these specific string constants". Make this more clear.
Test Plan: Viewed each call from the web UI.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T5058
Differential Revision: https://secure.phabricator.com/D9127