docs: update categories to match sidebar

[mayacoda]

Description of Change

The introduction documentation page describes each of the categories available in the sidebar, but some of the category titles didn't match.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• relevant documentation is changed or added
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: none

[welcome]

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[welcome]

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[release-clerk]

No Release Notes

[trop]

I have automatically backported this PR to "19-x-y", please check out #35201

[trop]

I have automatically backported this PR to "20-x-y", please check out #35202