allow CORS usage from browsers

[michaelneale]

index.html:1 Access to fetch at 'https://ion.tbd.engineering/didtype/1669' from origin 'null' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.```