(Bug) Modify Index Template to LogsDB (elastic#962)

👋 howdy, team! ( cc: @asmith-elastic @anniegale9538 for Sev1 01849100 )

The existing docs for Creating LogsDB
([v8](https://www.elastic.co/guide/en/elasticsearch/reference/current/logs-data-stream.html#how-to-use-logsds),
[v9](https://docs-v3-preview.elastic.dev/elastic/docs-content/tree/main/manage-data/data-store/data-streams/logs-data-stream);
believed ported via
elastic/elasticsearch#118303) has users create
an index template overriding previous which negates all Fleet-managed
Integration index pipelines which breaks ingestion patterns across all
`logs-*` 👻.

This adds in a warning header that for Fleet-managed integrations (which
AFAIK is the only major exception) users should instead be adding the
recommended setting [into the component template per existing
doc](https://www.elastic.co/guide/en/observability/current/logs-index-template.html#custom-logs-template-edit).
TIA!

---------

Co-authored-by: shainaraskas <[email protected]>

Author: stefnestor

manage-data/data-store/data-streams/logs-data-stream.md

@@ -20,12 +20,16 @@ In benchmarks, log data stored in a logs data stream used ~2.5 times less disk s
 
 ## Create a logs data stream [how-to-use-logsds]
 
+::::{important}
+Fleet integrations use [index templates](../templates.md) managed by Elastic. To modify these backing templates, update their [composite `custom` templates](/solutions/observability/logs/logs-index-template-reference.md##custom-logs-template-edit).
+::::
+
 To create a logs data stream, set your [template](../templates.md) `index.mode` to `logsdb`:
 
 ```console
 PUT _index_template/my-index-template
 {
-  "index_patterns": ["logs-*"],
+  "index_patterns": ["my-datastream-*"],
   "data_stream": { },
   "template": {
      "settings": {