docs: modify the wrong Chinese word

[whyer11]

"阀值" is a wrong word in Chinese, "阈值" should be used here

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe: documents

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• It's submitted to the dev branch.
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• All tests are passing: https://github.com/vuejs/vue-test-utils/blob/dev/.github/CONTRIBUTING.md#development-setup
• New/updated tests are included

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information:

[whyer11]

why checks all run failed?

[lmiller1990]

I guess we need to update the Netlify infrastructure. I have no idea how to do this, I will find out. Maybe @afontcu has some context 🤔 ?

[whyer11]

any update?

[lmiller1990]

I do not have access to the Netlify account to update the image, but I asked someone who does. Should be able to get this fixed this week.

[lmiller1990]

Still no luck. I miss GH pages, it was a lot easier that having to manage access to multiple tools. Maybe we should move back to that.

[lmiller1990]

Gonna merge this while I try to chase up a Netlify fix.