docs: Update differences.md

[bangank36]

Summary

• Shopify also has json filter, I think it is equivalent to liquidJS json
• See https://shopify.dev/docs/api/liquid/filters/json

Propose changes

• Remove the line * LiquidJS has additional filters: [json][json]. from the doc

[coveralls]

Pull Request Test Coverage Report for Build 4465426626

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 4461743521:	0.0%
Covered Lines:	2174
Relevant Lines:	2174

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💛 - Coveralls

[harttle]

@all-contributors please add @bangank36 for doc.

[allcontributors[bot]]

@harttle

I've put up a pull request to add @bangank36! :tada:

[github-actions[bot]]

:tada: This PR is included in version 10.7.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: