📝 Add docs annotations for source examples

docs_src/tutorial/delete/annotations/en/tutorial002.md

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+1. Select the hero we will delete.
+
+2. Execute the query with the select statement object.
+
+    This generates the output:
+
+    ```
+    INFO Engine BEGIN (implicit)
+    INFO Engine SELECT hero.id, hero.name, hero.secret_name, hero.age 
+    FROM hero 
+    WHERE hero.name = ?
+    INFO Engine [no key 0.00011s] ('Spider-Youngster',)
+    ```
+
+3. Get one hero object, expecting exactly one.
+
+    !!! tip
+        This ensures there's no more than one, and that there's exactly one, not `None`.
+
+        This would never return `None`, instead it would raise an exception.
+
+4. Print the hero object.
+
+    This generates the output:
+
+    ```
+    Hero:  name='Spider-Youngster' secret_name='Pedro Parqueador' age=16 id=2
+    ```
+
+5. Delete the hero from the **session**.
+
+    This marks the hero as deleted from the session, but it will not be removed from the database until we **commit** the changes.
+
+6. Commit the session.
+
+    This saves the changes in the session, including deleting this row.
+
+    It generates the output:
+
+    ```
+    INFO Engine DELETE FROM hero WHERE hero.id = ?
+    INFO Engine [generated in 0.00020s] (2,)
+    INFO Engine COMMIT
+    ```
+
+7. Print the deleted hero object.
+
+    The hero is deleted in the database. And is marked as deleted in the session.
+
+    But we still have the object in memory with its data, so we can use it to print it.
+
+    This generates the output:
+
+    ```
+    Deleted hero: name='Spider-Youngster' secret_name='Pedro Parqueador' age=16 id=2
+    ```
+
+8. Select the same hero again.
+
+    We'll do this to confirm if the hero is really deleted.
+
+9. Execute the select statement.
+
+    This generates the output:
+
+    ```
+    INFO Engine BEGIN (implicit)
+    INFO Engine SELECT hero.id, hero.name, hero.secret_name, hero.age 
+    FROM hero 
+    WHERE hero.name = ?
+    INFO Engine [no key 0.00013s] ('Spider-Youngster',)
+    ```
+
+10. Get the "first" item from the `results`.
+
+    If no items were found, this will return `None`, which is what we expect.
+
+11. Check if the first item from the results is `None`.
+
+12. If this first item is indeed `None`, it means that it was correctly deleted from the database.
+
+    Now we can print a message to confirm.
+
+    This generates the output:
+
+    ```
+    There's no hero named Spider-Youngster
+    ```
+
+13. This is the end of the `with` block, here the **session** executes its closing code.
+
+    This generates the output:
+
+    ```
+    INFO Engine ROLLBACK
+    ```