chore: Update contact_us link in 01_intro.md (#290)

# What ❔

- Update contact_us link in 01_intro.md

## Why ❔


![image](https://github.com/matter-labs/zksync-era/assets/148616461/8727b259-5c7b-4a42-b652-58b292560caa)

## Checklist

<!-- Check your PR fulfills the following items. -->
<!-- For draft PRs check the boxes as you complete them. -->

- [x] PR title corresponds to the body of PR (we generate changelog
entries from PRs).
- [ ] Tests for the changes have been added / updated.
- [ ] Documentation comments have been added / updated.
- [x] Code has been formatted via `zk fmt` and `zk lint`.

docs/external-node/01_intro.md

@@ -49,7 +49,7 @@ A more detailed overview of the EN's components is provided in the [components](
 API exposed by the EN strives to be Web3-compliant. If some method is exposed but behaves differently compared to
 Ethereum, it should be considered a bug. Please [report][contact_us] such cases.
 
-[contact_us]: https://docs.zksync.io/contact/
+[contact_us]: https://zksync.io/contact
 
 ### `eth` namespace