[Security] Moves Automatic Migration from preview to GA (#2290)

Contributes to
elastic/docs-content-internal#96.

Preview: [Automatic
migration](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/2290/solutions/security/get-started/automatic-migration)

8.19 PR: elastic/security-docs#6957

---------

Co-authored-by: florent-leborgne <[email protected]>

Author: natasha-moore-elastic

solutions/security/get-started/automatic-migration.md

@@ -1,15 +1,12 @@
 ---
 applies_to:
-  stack: preview
-  serverless: preview
+  stack: preview 9.0, ga 9.1
+  serverless:
+    security: ga
 ---
 
 # Automatic migration
 
-::::{warning}
-This feature is in technical preview. It may change in the future, and you should exercise caution when using it in production environments. Elastic will work to fix any issues, but features in technical preview are not subject to the support SLA of GA features.
-::::
-
 Automatic Migration for detection rules helps you quickly convert SIEM rules from the Splunk's Search Processing Language (SPL) to the Elasticsearch Query Language ({{esql}}). If comparable Elastic-authored rules exist, it simplifies onboarding by mapping your rules to them. Otherwise, it creates custom rules on the fly so you can verify and edit them instead of writing them from scratch.
 
 You can ingest your data before migrating your rules, or migrate your rules first in which case the tool will recommend which data sources you need to power your migrated rules.