Fix displaying testable example on pkg.go.dev

[alexandear]

Before submitting your PR, please confirm the following.

• Describe the purpose for which you created this PR.
• Create test code that corresponds to the modification

The repo contains 11 testable examples, but on the https://pkg.go.dev/github.com/goccy/go-yaml@v1.15.9#pkg-examples there is only 1 example listed. This PR fixes that all examples will be listed after merging.

Before:

After:

Explanation https://go.dev/blog/examples#example-function-names

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.37%. Comparing base (342293d) to head (3476ea0).

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #587   +/-   ##
=======================================
  Coverage   77.37%   77.37%           
=======================================
  Files          21       21           
  Lines        7704     7704           
=======================================
  Hits         5961     5961           
  Misses       1333     1333           
  Partials      410      410           

[goccy]

Thank you for your great PR!

[alexandear]

Examples can be seen here or here after releasing a new version.