basic-features: collapse charset and collations (#6452)

[ti-chi-bot]

This is an automated cherry-pick of #6452

What is changed, added or deleted? (Required)

It looks a bit strange on https://docs.pingcap.com/tidb/dev/basic-features because you have to scroll for quite a while until there is something different between versions. This will probably always be the case given the very quick release-cycle.

As a partial fix, this collapses charset and collations to take up less screen realestate.

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[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.

Commit hash: fd09000