Docs: AI chatbot tutorial.

[technically-tracy]

(Describe the goal of this PR. Mention any related Issue numbers)

Category (place an x in each of the [ ])

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

Requirements (place an x in each [ ])

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

• [x] I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• [x] 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[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 91.99%. Comparing base (cee9455) to head (7fd9b45). Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1141   +/-   ##
=======================================
  Coverage   91.99%   91.99%           
=======================================
  Files         195      195           
  Lines        6621     6621           
=======================================
  Hits         6091     6091           
  Misses        530      530           

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