Add expo-update example for bare RN apps (#11612)

Author: filipef101

docs/platforms/react-native/sourcemaps/uploading/expo.mdx

@@ -37,15 +37,25 @@ eas update
 To upload source maps for all platforms use the following command:
 
 ```bash
+SENTRY_AUTH_TOKEN=___ORG_AUTH_TOKEN___ \
+npx sentry-expo-upload-sourcemaps dist
+```
+
+To upload source maps without expo plugin (bare workflow):
+
+```bash
+SENTRY_AUTH_TOKEN=___ORG_AUTH_TOKEN___ \
 SENTRY_PROJECT=___PROJECT_SLUG___ \
 SENTRY_ORG=___ORG_SLUG___ \
-SENTRY_AUTH_TOKEN=___ORG_AUTH_TOKEN___ \
+SENTRY_URL=https://sentry.io/ \
 npx sentry-expo-upload-sourcemaps dist
 ```
 
+
 #### Notes
 
 - `dist` is the default output directory of `eas update`.
+- Sentry Org, Sentry Project, and Sentry Url will be loaded from the expo plugin config (app.json / app.config.js) if the environment variable isn't set.
 - Uploaded source maps have no associated releases. This is expected as updates can apply to multiple releases.
 
 ## Notes