Update develop/toolkit/integrations/transaction-construction.md

Co-authored-by: Copilot <[email protected]>

Author: brunopgalvao

develop/toolkit/integrations/transaction-construction.md

@@ -58,7 +58,7 @@ The mode and metadataHash fields were introduced in transaction construction to
 This enables trustless metadata verification by allowing the chain to verify the correctness of the
 metadata used without the need of a trusted party. This functionality was included in
 [v1.2.5](https://github.com/polkadot-fellows/runtimes/releases/tag/v1.2.5) runtime release by the
-Fellowship. A user may up out of this functionality by setting the mode to `0`. When the mode is 00,
+Fellowship. A user may opt out of this functionality by setting the mode to `0`. When the mode is 00,
 the `metadataHash` field is empty/None.
 
 **Serialized transactions and metadata**