docs: Fix deprecation message for span data/attributes

[mydea]

This was apparently left over from some in-between state, users should actually use spanToJSON(span) there to get attributes.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay, Feedback) - Webpack (gzipped)	78.09 KB (-0.1% 🔽)
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	69.29 KB (-0.12% 🔽)
@sentry/browser (incl. Tracing, Replay with Canvas) - Webpack (gzipped)	73.23 KB (-0.12% 🔽)
@sentry/browser (incl. Tracing, Replay) - Webpack with treeshaking flags (gzipped)	62.93 KB (-0.13% 🔽)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	33.27 KB (-0.25% 🔽)
@sentry/browser (incl. browserTracingIntegration) - Webpack (gzipped)	33.13 KB (-0.25% 🔽)
@sentry/browser (incl. Feedback) - Webpack (gzipped)	31.15 KB (-0.15% 🔽)
@sentry/browser (incl. sendFeedback) - Webpack (gzipped)	31.15 KB (-0.19% 🔽)
@sentry/browser - Webpack (gzipped)	22.4 KB (-0.35% 🔽)
@sentry/browser (incl. Tracing, Replay, Feedback) - ES6 CDN Bundle (gzipped)	76.06 KB (-0.17% 🔽)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	67.59 KB (-0.18% 🔽)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	33.37 KB (-0.32% 🔽)
@sentry/browser - ES6 CDN Bundle (gzipped)	24.46 KB (-0.41% 🔽)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	213.21 KB (-0.22% 🔽)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	101.03 KB (-0.44% 🔽)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	73.42 KB (-0.6% 🔽)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	36.54 KB (-0.28% 🔽)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	69.68 KB (-0.13% 🔽)
@sentry/react - Webpack (gzipped)	22.45 KB (-0.3% 🔽)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	87.43 KB (-0.13% 🔽)
@sentry/nextjs Client - Webpack (gzipped)	50.35 KB (-0.14% 🔽)
@sentry-internal/feedback - Webpack (gzipped)	17.12 KB (-0.48% 🔽)

[krystofwoldrich]

Thank you! 🚀