Update datamodel.prisma

Author: nikolasburk

server/prisma/datamodel.prisma

@@ -1,14 +1,14 @@
 type Link {
-  id: ID! @unique
-  createdAt: DateTime!
+  id: ID! @id
+  createdAt: DateTime! @createdAt
   description: String!
   url: String!
   postedBy: User
   votes: [Vote!]!
 }
 
 type User {
-  id: ID! @unique
+  id: ID! @id
   name: String!
   email: String! @unique
   password: String!
@@ -17,7 +17,7 @@ type User {
 }
 
 type Vote {
-  id: ID! @unique
+  id: ID! @id
   link: Link!
   user: User!
-}
+}