chore: small fix in readme (#21127)

Author: facundomedica

x/tx/CHANGELOG.md

@@ -35,7 +35,7 @@ Since v0.13.0, x/tx follows Cosmos SDK semver: https://github.com/cosmos/cosmos-
 
 ### Improvements
 
-* [#21073](https://github.com/cosmos/cosmos-sdk/pull/21073) In Context use sync.Map `getSignersFuncs` map from concurrent writes, we also call Validate when creating the Context.
+* [#21073](https://github.com/cosmos/cosmos-sdk/pull/21073) In Context use sync.Map `getSignersFuncs` map from concurrent writes, we also need to call Validate when using the legacy app.
 
 ## [v0.13.3](https://github.com/cosmos/cosmos-sdk/releases/tag/x/tx/v0.13.3) - 2024-04-22