Fix #372 by adding listener matcher docs

[seratch]

This pull request fixes #372 by updating the document about listener matchers.

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
• 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.

• 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

Merging #402 (108ba90) into main (007d278) will increase coverage by 2.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #402      +/-   ##
==========================================
+ Coverage   89.65%   91.72%   +2.07%     
==========================================
  Files         128      167      +39     
  Lines        3585     5437    +1852     
==========================================
+ Hits         3214     4987    +1773     
- Misses        371      450      +79     

Impacted Files	Coverage Δ
slack_bolt/util/utils.py	84.61% <0.00%> (-5.87%)	⬇️
slack_bolt/request/async_request.py	94.28% <0.00%> (-5.72%)	⬇️
slack_bolt/request/async_internals.py	96.15% <0.00%> (-3.85%)	⬇️
slack_bolt/request/request.py	97.05% <0.00%> (-2.95%)	⬇️
slack_bolt/adapter/aws_lambda/chalice_handler.py	84.28% <0.00%> (-2.39%)	⬇️
slack_bolt/oauth/internals.py	97.77% <0.00%> (-2.23%)	⬇️
slack_bolt/version.py	100.00% <0.00%> (ø)
slack_bolt/__init__.py	100.00% <0.00%> (ø)
slack_bolt/async_app.py	100.00% <0.00%> (ø)
slack_bolt/app/__init__.py	100.00% <0.00%> (ø)
... and 128 more

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[seratch]

Let me merge this but please feel free to write in if you see something we can improve even after that!