*: update some sentences. (#5346)

[ti-srebot]

cherry-pick #5346 to release-5.0
You can switch your code base to this Pull Request by using git-extras:

# In docs repo:
git pr https://github.com/pingcap/docs/pull/5348

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/docs.git pr/5348:release-5.0-568da8684c32

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What is changed, added or deleted? (Required)

A tiny update to modify some sentences.

Which TiDB version(s) do your changes apply to? (Required)

• master (the latest development version)
• v5.0 (TiDB 5.0 versions)
• v4.0 (TiDB 4.0 versions)
• v3.1 (TiDB 3.1 versions)
• v3.0 (TiDB 3.0 versions)
• v2.1 (TiDB 2.1 versions)

What is the related PR or file link(s)?

• This PR is translated from:
• Other reference link(s):

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

[ti-srebot]

@bb7133 please accept the invitation then you can push to the cherry-pick pull requests.
https://github.com/ti-srebot/docs/invitations

[TomShawn]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• TomShawn

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[TomShawn]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

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Commit hash: 4c25f2b