fix: correct contribute documentation preview locally (#1532)

[dianacheung]

What/Why/How?

fixed the incorrect command to preview local docs changes in contributing.md

Reference

#1532

Testing

vscode preview of markdown file contributing.md
ran vale \docs
checked with markdownlint vscode extension

[changeset-bot]

⚠️ No Changeset found

Latest commit: a466c91

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[lornajane]

Thanks @dianacheung !