docs(examples): update examples for refactored components

[JRocabruna]

Description

This pull request updates the examples to reflect the recent changes in the project structure. The examples have been updated to use the new structure and demonstrate the correct usage of the refactored components.

• Related Issue: Closes #22
• Type of Change:
  • New feature (non-breaking change which adds functionality)
  • This change requires a documentation update

Checklist

Please ensure the following guidelines are met:

• [x] The code follows the style guidelines of this project.
• [x] A self-review has been performed on the code.
• [x] The code is well-documented, and comments have been added where necessary.
• [x] Tests have been added to prove that the fix is effective or that the feature works. All existing tests pass.
• [x] Commit messages follow the convention type(scope): description.
• [x] The pull request has no conflicts with the base branch.
• [x] Any dependent changes have been merged and published in downstream modules.

Additional Information

This update improves the clarity and usability of the examples, ensuring they are aligned with the latest changes in the project structure. The updated examples serve as a better guide for users to understand how to integrate and use the gomail library effectively.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

@@           Coverage Diff            @@
##           develop      #28   +/-   ##
========================================
  Coverage    92.31%   92.31%           
========================================
  Files           14       14           
  Lines          807      807           
========================================
  Hits           745      745           
  Misses          34       34           
  Partials        28       28           

Flag	Coverage Δ
unittests	92.31% <0.00%> (ø)

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