Fix #1237 Updates to message subtypes doc

[wongjas]

Summary

Fixes #1237 for both EN and JP docs. Changes message subtype from bot_message to message_changed and makes it explicit to import subtype from the Bolt package.

Requirements (place an x in each [ ])

• 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.

[seratch]

I know the usage of console is not your change but we may want to improve the part as well. Can you change the code this way? It's the same for the English one.

Suggested change

	app.message(subtype('message_changed'), ({ event }) => {
	console.log(`The user ${event.message.user} changed their message from ${event.previous_message.text} to ${event.message.text}`);
	app.message(subtype('message_changed'), ({ event, logger }) => {
	logger.info(`The user ${event.message.user} changed their message from ${event.previous_message.text} to ${event.message.text}`);

[wongjas]

Yeah, that makes sense. Maybe we should change it for the entirety of the docs? It looks like console.log is used throughout at the moment.

[seratch]

Oh I see. In the case, let's work on the replacement in a different issue/PR!

[codecov]

Codecov Report

Merging #1240 (a2a9ca9) into main (9658caa) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1240   +/-   ##
=======================================
  Coverage   73.22%   73.22%           
=======================================
  Files          17       17           
  Lines        1438     1438           
  Branches      431      431           
=======================================
  Hits         1053     1053           
  Misses        300      300           
  Partials       85       85           

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[seratch]

Looks good to me. @srajiang if this looks good to you too, can you "squash and merge" this PR tomorrow in your local time?

[wongjas]

Conflicts have been resolved ✅