Update setup docs

docs/setup.en.md

@@ -131,6 +131,7 @@ You can check if the service is running with `systemctl status misskey`.
 2. `git checkout $(git tag -l | grep -v 'rc[0-9]*$' | sort -V | tail -n 1)`
 3. `npm install`
 4. `npm run build`
+5. Check [ChangeLog](../CHANGELOG.md) for migration information
 
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docs/setup.ja.md

@@ -120,6 +120,7 @@ WantedBy=multi-user.target
 2. `git checkout $(git tag -l | grep -v 'rc[0-9]*$' | sort -V | tail -n 1)`
 3. `npm install`
 4. `npm run build`
+5. [ChangeLog](../CHANGELOG.md)でマイグレーション情報を確認する
 
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