Just finished reading draft 19 of the updated Discovery spec.
The only comment I have is regarding http://openid.bitbucket.org/openid-connect-discovery-1_0.html#ProviderConfigurationResponse
"Claims that return multiple values are represented as JSON arrays. Claims with zero elements MUST be omitted from the response."
The first sentence is a bit ambiguous, I suggest we remove it entirely and just let readers refer to section 3 for the expected member value types.
Other than that everything seems fine! Good work!