Add Type Adapter Docs example codes & information about dump_json()

[WinterBlue16]

Change Summary

• Add example to dump_json()
• Add information about dump_json() return bytes not like .model_dump_json()

Related issue number

#9474

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

[codspeed-hq]

CodSpeed Performance Report

Merging #9477 will not alter performance

_{Comparing WinterBlue16:main (c1a83c5) with main (bcac9a2)}

Summary

✅ 13 untouched benchmarks

[sydney-runkle]

Hi @WinterBlue16,

Thanks for your contribution to our docs! I'm going to do a few minor wording updates, then will merge this! Great work!