Update Collection.md

Changed the error type from ValueError to DuplicateIDError for add function in collections

Author: ramaravilli

docs/reference/Collection.md

@@ -52,7 +52,7 @@ Add embeddings to the data store.
 - `ValueError` - If the length of ids, embeddings, metadatas, or documents don't match
 - `ValueError` - If you don't provide an embedding function and don't provide embeddings
 - `ValueError` - If you provide both embeddings and documents
-- `ValueError` - If you provide an id that already exists
+- `DuplicateIDError` - If you provide an id that already exists
 
 ### get