fix: Improve <TableOfContents> to allow empty sections

[mydea]

Not sure why I even added this, but this seems unnecessary!

Closes #13159

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
develop-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Mar 31, 2025 3:10pm
sentry-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Mar 31, 2025 3:10pm

1 Skipped Deployment

Name	Status	Preview	Comments	Updated (UTC)
changelog	⬜️ Ignored (Inspect)			Mar 31, 2025 3:10pm

[codecov]

Bundle Report

Changes will decrease total bundle size by 46 bytes (-0.0%) ⬇️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
sentry-docs-server-cjs	10.61MB	-9 bytes (-0.0%) ⬇️
sentry-docs-client-array-push	9.44MB	-37 bytes (-0.0%) ⬇️

Affected Assets, Files, and Routes:

view changes for bundle: sentry-docs-client-array-push

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
static/chunks/pages/_app-*.js	-3 bytes	868.67kB	-0.0%
static/chunks/8931-*.js	-3 bytes	397.42kB	-0.0%
static/chunks/app/[[...path]]/page-*.js	-31 bytes	77.86kB	-0.04%
static/29whE1BOitPWlNbSxc75v/_buildManifest.js (New)	578 bytes	578 bytes	100.0% 🚀
static/29whE1BOitPWlNbSxc75v/_ssgManifest.js (New)	77 bytes	77 bytes	100.0% 🚀
static/oWDKXWNl_DQrLrJUysx5W/_buildManifest.js (Deleted)	-578 bytes	0 bytes	-100.0% 🗑️
static/oWDKXWNl_DQrLrJUysx5W/_ssgManifest.js (Deleted)	-77 bytes	0 bytes	-100.0% 🗑️

Files in static/chunks/app/[[...path]]/page-*.js:

• ./src/components/tableOfContents.tsx → Total Size: 2.98kB

view changes for bundle: sentry-docs-server-cjs

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
1729.js	-3 bytes	1.58MB	-0.0%
../instrumentation.js	-3 bytes	911.63kB	-0.0%
9523.js	-3 bytes	887.68kB	-0.0%

[inventarSarah]

Awesome, thanks for the quick update -- I'll use the component in #13138 as soon as this is merged 🎉