prerelease-dev-3be5e48

chore: dead link docs in CONTRIBUTING.md (#18)

# What ❔

Hi! I updates a dead link in the CONTRIBUTING.md file. The old link
pointing to era.zksync.io/docs/ has been replaced with the correct URL
https://docs.zksync.io/zksync-era. This ensures that contributors are
directed to the correct and up-to-date documentation.

## Checklist

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- [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.
- [ ] Code has been formatted via `zk fmt` and `zk lint`.