[DOCS-14630] Document RUM event ingestion-to-visibility latency (#37624)

* [DOCS-14630] Document RUM event ingestion-to-visibility latency

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Soften latency wording to avoid committing to a specific figure

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Add troubleshooting link to setup start monitoring section

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Add retention filter nuance to RUM ingestion latency

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* add link to retention filter page

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: rtrieu

layouts/shortcodes/mdoc/en/sdk/setup/browser.mdoc.md

@@ -362,7 +362,7 @@ To request support for a web server that is not listed here, [fill out this form
 
 Visualize the [data collected][11] in [dashboards][12] or create a search query in the [RUM Explorer][5].
 
-Your application appears as pending on the Applications page until Datadog starts receiving data.
+Your application appears as pending on the Applications page until Datadog starts receiving data. If data takes time to appear, see [Troubleshooting Browser SDK Issues][15].
 
 [1]: /real_user_monitoring/
 [2]: /error_tracking/frontend/browser
@@ -378,4 +378,5 @@ Your application appears as pending on the Applications page until Datadog start
 [12]: /real_user_monitoring/platform/dashboards/
 [13]: /private-beta/rum-sdk-auto-injection/
 [14]: /real_user_monitoring/application_monitoring/browser/setup/client
+[15]: /real_user_monitoring/browser/troubleshooting/#data-to-the-datadog-intake
 

layouts/shortcodes/mdoc/en/sdk/troubleshooting/browser.mdoc.md

@@ -51,6 +51,8 @@ If data is being sent, you should see network requests targeting `api/v2/rum` (t
 
 {% img src="real_user_monitoring/browser/troubleshooting/network_intake-1.png" alt="RUM requests to Datadog intake" /%}
 
+After the data reaches the intake, availability in the Datadog UI depends on your retention filter configuration. If the session is retained, events typically appear in the RUM Explorer within a few seconds after the [retention decision][17] is made. Otherwise, it may take a few minutes.
+
 ## RUM cookies
 
 The RUM Browser SDK relies on cookies to store session information and follow a [user session][7] across different pages. The cookies are first-party (they are set on your domain) and are not used for cross-site tracking. Here are the cookies set by the RUM Browser SDK:
@@ -153,3 +155,4 @@ A warning appears when deobfuscation fails for a stack trace. If the stack trace
 [14]: https://app.datadoghq.com/source-code/setup/rum
 [15]: /real_user_monitoring/guide/debug-symbols
 [16]: /real_user_monitoring/#technical-limitations
+[17]: /real_user_monitoring/rum_without_limits/retention_filters