flutter: feature flags docs

[buenaflor]

This is the copy of #13391 since it has some codeowner CI problems as it was created by a contractor.

The PR that this was copied from has been approved so this one can be approved as well

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
develop-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 16, 2025 1:58pm
sentry-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jun 16, 2025 1:58pm

[codecov]

Bundle Report

Changes will increase total bundle size by 1.03kB (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
sentry-docs-server-cjs	10.92MB	900 bytes (0.01%) ⬆️
sentry-docs-edge-server-array-push	371.51kB	134 bytes (0.04%) ⬆️
sentry-docs-client-array-push	9.77MB	-6 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	873.24kB	-0.0%
static/chunks/7750-*.js	-3 bytes	401.83kB	-0.0%
server/middleware-*.js	5.55kB	6.55kB	555.3% ⚠️
server/middleware-*.js	-5.55kB	1.0kB	-84.74%
static/j0qE-*.js (New)	77 bytes	77 bytes	100.0% 🚀
static/j0qE-*.js (New)	616 bytes	616 bytes	100.0% 🚀
static/nrTMLpPRT8SuGEEFeJ5mP/_buildManifest.js (Deleted)	-616 bytes	0 bytes	-100.0% 🗑️
static/nrTMLpPRT8SuGEEFeJ5mP/_ssgManifest.js (Deleted)	-77 bytes	0 bytes	-100.0% 🗑️

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

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
1729.js	-3 bytes	1.64MB	-0.0%
../instrumentation.js	-3 bytes	973.36kB	-0.0%
9523.js	-3 bytes	949.31kB	-0.0%
../app/[[...path]]/page.js.nft.json	303 bytes	400.78kB	0.08%
../app/platform-redirect/page.js.nft.json	303 bytes	400.7kB	0.08%
../app/sitemap.xml/route.js.nft.json	303 bytes	398.67kB	0.08%

view changes for bundle: sentry-docs-edge-server-array-push

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
src/middleware.js	134 bytes	207.51kB	0.06%