Improve view_submission listener document to mention ack() + response_action patterns

[seratch]

Description

We've received similar questions before but as you can see here: #1123 (comment), using ack() with response_action over views.update API method in view_submission listeners is not obvious for developers. We can improve this document section to mention the proper way to update a modal in response to view_submission.

What type of issue is this? (place an x in one of the [ ])

• bug
• enhancement (feature request)
• question
• documentation related
• example code related
• testing related
• discussion

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

• 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 searched for any related issues and avoided creating a duplicate issue.

[seratch]

This is the same for bolt-python: https://slack.dev/bolt-python/concepts#view_submissions

As for bolt-java, the document page structure is not the same and it already has some guide for it:

You respond to "view_submission" requests with response_action to determine the next state of a modal
Call ack() as an acknowledgment with either of the followings:
Sending an empty body means closing only the modal
Sending a body with response_action (possible values are "errors", "update", "push", "clear")
https://slack.dev/java-slack-sdk/guides/modals#view_submission-requests-1