chore: update youtube link in readme (#171)

## What ❔

* [x] Update YouTube link in the README file for a correct one

<!-- What are the changes this PR brings about? -->
<!-- Example: This PR adds a PR template to the repo. -->
<!-- (For bigger PRs adding more context is appreciated) -->

## Why ❔

The previous one was outdated.

<!-- Why are these changes done? What goal do they contribute to? What
are the principles behind them? -->
<!-- The `Why` has to be clear to non-Matter Labs entities running their
own ZK Chain -->
<!-- Example: PR templates ensure PR reviewers, observers, and future
iterators are in context about the evolution of repos. -->

## Is this a breaking change?
- [ ] Yes
- [x] No

## 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).
- [x] Tests for the changes have been added / updated.
- [x] Documentation comments have been added / updated.
- [x] Code has been formatted.

Author: antonbaliasnikov

README.md

@@ -60,11 +60,11 @@ Details on third-party notices can be found in [NOTICE.md](./NOTICE.md), in `ACK
 - [Twitter for Developers](https://twitter.com/zkSyncDevs)
 - [Discord](https://join.zksync.dev/)
 - [Mirror](https://zksync.mirror.xyz/)
-- [YouTube](https://www.youtube.com/@zkSync-era)
+- [YouTube](https://www.youtube.com/@zksync-io)
 
 ## Contribution
 
 Unless you explicitly state otherwise, any contribution intentionally
 submitted for inclusion in the work by you, as defined in the Apache-2.0
 license, shall be dual licensed as above, without any additional terms or
-conditions.
+conditions.