Fix validation for `doctrine`

app/models/doctrine.rb

@@ -9,8 +9,7 @@ class Doctrine < ApplicationRecord
 
   has_many :annotations, dependent: :destroy
 
-  validates :content, presence: true
+  validates :content, :headnote, presence: true
-  validates :content_fingerprint, uniqueness: true
 
   before_validation do
     self.content_fingerprint = Digest::SHA256.hexdigest(content)