docs(*): update README.md

[lumirlumir]

This pull request makes several improvements and clarifications to the README.md for the textlint-rule-allowed-uris package. The main updates include clarifying documentation around URI pattern matching, improving example links, and updating configuration examples to include a new option.

Documentation improvements:

• Updated the link to detailed Markdown examples to point directly to the "links" section for better navigation.
• Clarified the language to state that only regular expressions are allowed for URI pattern matching, making the restriction explicit.

Configuration example updates:

• Added the checkUnusedDefinitions: false option to all configuration examples to document this available setting. [1] [2] [3] [4]

[Copilot]

Pull Request Overview

This pull request improves the documentation in the README.md file for the textlint-rule-allowed-uris package. The changes enhance clarity around URI pattern matching and provide more complete configuration examples.

• Updated external link to point directly to the "links" section for better navigation
• Clarified that only regular expressions are allowed for URI pattern matching
• Added checkUnusedDefinitions: false option to all configuration examples

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[github-actions]

Labels have been automatically applied based on the Conventional Commits specification.🏷️

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (5818eb3) to head (3834675).
⚠️ Report is 1 commits behind head on main.

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  Coverage   100.00%   100.00%           
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  Files            2         2           
  Lines          257       257           
  Branches         1         1           
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  Hits           257       257           

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