Link to docs for timing-allow-origin alert with examples

[AbhiPrasad]

A user wrote asking for assistance with debugging their timing-allow-origin setup for their production CDN. We should link the warning banner in resource module and span details to a troubleshooting docs page with relevant examples.

See related user feedback: https://sentry.sentry.io/feedback/?feedbackSlug=javascript:4807361749&project=11276

sentry/static/app/views/performance/browser/resources/resourceSummaryPage/resourceInfo.tsx

Line 113 in 341e1de

"We couldn't find any size information for this resource, this is likely because the `timing-allow-origin` header is not set."

sentry/static/app/components/events/interfaces/spans/newTraceDetailsSpanDetails.tsx

Line 528 in 341e1de

<span className="val-string">Timing-Allow-Origin</span>

[camjackson-bigwx]

In lieu of proper docs being added and linked to from the banner, would you mind providing some guidance here @AbhiPrasad?

I understand I need to add Timing-Alllow-Origin: <some-domain> as a response header in my application, but I'm not sure what to set it to? sentry.io? Something else?

[AbhiPrasad]

Hey @camjackson-bigwx sorry for the delay - clearing the my backlog after vacation.

You need to set Timing-Allow-Origin to the domain that your frontend is on. This allows the browser APIs (which the Sentry SDKs are using) to collect the information.

cc @bcoe