Inline single constant values

[kpdecker]

    errorCode: Joi.string().equal(Account.USER_DOES_NOT_EXIST)

Renders as:

Ideally we simplify this to something like

  errorCode: 'user_does_not_exist'

Potentially may want to consider inlining all enum options, i.e.:

  errorCode: one of "user_does_not_exist"

Since the type display doesn't mean too much since we only allow a valid subset of what the full type is.

[Marsup]

Agreed, do you want to take it ?

[kpdecker]

I'm playing around so I can try to do a PR for this.