docs: update learn/beginner docs (backport #22191)

[mergify]

Description

Ref:
#21429

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Author Checklist

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I have...

• included the correct type prefix in the PR title, you can find examples of the prefixes below:

• confirmed ! in the type prefix if API or client breaking change

• targeted the correct branch (see PR Targeting)

• provided a link to the relevant issue or specification

• reviewed "Files changed" and left comments if necessary

• included the necessary unit and integration tests

• added a changelog entry to CHANGELOG.md

• updated the relevant documentation or specification, including comments for documenting Go code

• confirmed all CI checks have passed

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• confirmed the correct type prefix in the PR title
• confirmed all author checklist items have been addressed
• reviewed state machine logic, API design and naming, documentation is accurate, tests and test coverage

Summary by CodeRabbit

• Documentation
  • Enhanced clarity and updated references across several documents regarding app anatomy, transaction lifecycle, query lifecycle, accounts, and gas fees.
  • Improved explanations of transaction creation, processing, and query handling.
  • Updated URLs and method signatures to reflect the latest Cosmos SDK version.
  • Corrected grammatical errors and refined language for better readability.

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This is an automatic backport of pull request #22191 done by [Mergify](https://mergify.com).