fix: update the release instructions

[WilliamBergamin]

Summary

These changes improve the release instructions to be clearer

Testing

N/A

Category

• slack_bolt.App and/or its core components
• slack_bolt.async_app.AsyncApp and/or its core components
• Adapters in slack_bolt.adapter
• Document pages under /docs
• Others

Requirements

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you are agreeing to those rules.

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run ./scripts/install_all_and_run_tests.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.54%. Comparing base (9cba291) to head (ff89f1c).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@ Coverage Diff @@## main #1400 +/- ##
=======================================
Coverage 90.54% 90.54% =======================================
Files 222 222 Lines 7129 7129 =======================================
Hits 6455 6455 Misses 674 674 

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[mwbrooks]

✅ Thanks for the tightening up the release steps!