docs(react-native): Update the docs in accordance to how the current structure of an Expo project looks like

[alwx]

A relatively minor change: the current version of docs for Expo seems a bit outdated in a sense that it asks you to make a change to the project that doesn't match the actual project that's being generated by Expo.
This PR fixes that and makes it a bit easier for newcomers to understand what changes need to be made.

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
sentry-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Aug 4, 2025 4:23pm

1 Skipped Deployment

Name	Status	Preview	Comments	Updated (UTC)
develop-docs	⬜️ Ignored (Inspect)			Aug 4, 2025 4:23pm

[codecov]

Bundle Report

Changes will increase total bundle size by 180 bytes (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
sentry-docs-client-array-push	9.85MB	-6 bytes (-0.0%) ⬇️
sentry-docs-server-cjs	12.36MB	186 bytes (0.0%) ⬆️

Affected Assets, Files, and Routes:

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

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
1729.js	-3 bytes	1.77MB	-0.0%
../instrumentation.js	-3 bytes	1.1MB	-0.0%
9523.js	-3 bytes	1.08MB	-0.0%
../app/[[...path]]/page.js.nft.json	65 bytes	738.26kB	0.01%
../app/platform-redirect/page.js.nft.json	65 bytes	738.18kB	0.01%
../app/sitemap.xml/route.js.nft.json	65 bytes	735.65kB	0.01%

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	882.71kB	-0.0%
static/chunks/8321-*.js	-3 bytes	425.87kB	-0.0%
static/cb2eW02LMua0jTrLhklNI/_buildManifest.js (New)	684 bytes	684 bytes	100.0% 🚀
static/cb2eW02LMua0jTrLhklNI/_ssgManifest.js (New)	77 bytes	77 bytes	100.0% 🚀
static/lF-*.js (Deleted)	-77 bytes	0 bytes	-100.0% 🗑️
static/lF-*.js (Deleted)	-684 bytes	0 bytes	-100.0% 🗑️

[antonis]

LGTM 🚀
Thank you for catching this and opening a PR @alwx 🙇