[Docs] Add comment about isFieldDuplicated func.

Author: SHcommit

Sources/SHFirestoreService/FirestoreQueryable.swift

@@ -33,7 +33,17 @@ public protocol FirestoreQueryable {
         E: FirestoreEndopintable,
         D == E.ResponseDTO
 
-  /// Check if a document is duplicated or not from the endpoint requestType is a collectionRef using firestore's query.
+  /// Checks if a document is duplicated or not from the endpoint requestType is a collectionRef using firestore's query.
+  ///
+  /// This method executes a Firestore query to check if the specified field in the document is duplicated from a collection reference.
+  /// The query is executed using the provided endpoint and query handler.
+  ///
+  /// - Parameters:
+  ///   - endpoint: The Firestore endpoint to query, which must conform to `FirestoreEndopintable`.
+  ///   - query: The Firestore query handler used to execute the query.
+  ///            The query should be designed to check for field duplication.
+  /// - Returns: A publisher that emits a `Bool` indicating whether the field is duplicated (`true`) or not (`false`).
+  /// - Throws: `FirestoreServiceError` if the query execution fails.
   func isFieldDuplicated(
     endpoint: any FirestoreEndopintable,
     from query: FirestoreQueryHandler