Broken Link in `Add offchain workers`

### Broken Link

[Build a local blockchain](https://docs.substrate.io/tutorials/build-a-blockchain/build-local-blockchain/)
[Offchain worker demo](https://github.com/jimmychu0807/substrate-offchain-worker-demo/tree/v2.0.0/pallets/ocw)

### Expected Location

_No response_

### Context and Origin

_No response_