Explain the ':'-embedded convention for fields with several values

lib/GEODE/Metadata/Contrastive.hs

@@ -13,6 +13,10 @@ import GHC.Generics (Generic)
 newtype MultiText = MultiText
   { getList :: [Text] } deriving (Show)
 
+-- | We represent fields with multiple values by ':'-surrounded values
+-- (including a leading and trailing ':') to be able to always write the same
+-- regex to match for their value (/.*:Géographie:.*/, no matter if it occurs at
+-- the begining, the end or in the middle of the field
 formatList :: MultiText -> Text
 formatList = colonFormat . getList
   where