Fix issues spotted by @fredZen in #1802

app/models/attestation_template.rb

@@ -50,6 +50,9 @@ class AttestationTemplate < ApplicationRecord
   def used_tags
     delimiters_regex = /--(?<capture>((?!--).)*)--/
 
+    # We can't use flat_map as scan will return 3 levels of array,
+    # using flat_map would give us 2, whereas flatten will
+    # give us 1, which is what we want
     [title, body]
       .map { |str| str.scan(delimiters_regex) }
       .flatten