[8.16] [Docs] Fix collapsibles in RNs (elastic#199508) (elastic#199513)

# Backport

This will backport the following commits from `main` to `8.16`:
- [[Docs] Fix collapsibles in RNs
(elastic#199508)](elastic#199508)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

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Fix collapsibles in RNs (elastic#199508)\n\nThis PR fixes some formatting in
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Fix collapsibles in
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Co-authored-by: florent-leborgne <[email protected]>

docs/CHANGELOG.asciidoc

@@ -94,7 +94,7 @@ Deprecated functionality does not have an immediate impact on your application,
 you make the necessary updates after you upgrade to 8.16.0.
 
 [discrete]
-* The Logs Stream is now hidden by default in favor of the Logs Explorer app.
+.The Logs Stream is now hidden by default in favor of the Logs Explorer app.
 [%collapsible]
 ====
 *Details* +
@@ -105,7 +105,7 @@ You can still show the Logs Stream app again by navigating to Stack Management >
 ====
 
 [discrete]
-* Deprecates the Observability AI Assistant specific advanced setting `observability:aiAssistantLogsIndexPattern`.
+.Deprecates the Observability AI Assistant specific advanced setting `observability:aiAssistantLogsIndexPattern`.
 [%collapsible]
 ====
 *Details* +

docs/upgrade-notes.asciidoc

@@ -1674,19 +1674,16 @@ When you create *Lens* visualization, the default for the *Legend width* is now
 
 [discrete]
 [[deprecation-192003]]
-* Deprecated the Observability AI Assistant specific advanced setting `observability:aiAssistantLogsIndexPattern`. (8.16)
+.Deprecated the Observability AI Assistant specific advanced setting `observability:aiAssistantLogsIndexPattern`. (8.16)
 [%collapsible]
 ====
 *Details* +
 The Observability AI Assistant specific advanced setting for Logs index patterns `observability:aiAssistantLogsIndexPattern` is deprecated and no longer used. The AI Assistant will now use the existing **Log sources** setting `observability:logSources` instead. For more information, refer to ({kibana-pull}192003[#192003]).
-
-//*Impact* +
-//!!TODO!!
 ====
 
 [discrete]
 [[deprecation-194519]]
-* The Logs Stream was hidden by default in favor of the Logs Explorer app. (8.16)
+.The Logs Stream was hidden by default in favor of the Logs Explorer app. (8.16)
 [%collapsible]
 ====
 *Details* +