Update index.mdx

Clarifying the deprecation message to avoid any confusion. A customer was confused about the alert message explaining that Splunk Cloud is supported.

Author: InterstellarStella

docs/organization/integrations/data-visualization/splunk/index.mdx

@@ -5,7 +5,7 @@ description: "Learn more about Sentry's Splunk integration, which allows you to
 ---
 <Alert>
 
-Splunk integration is deprecated and is not availble to be installed on new projects.
+Splunk integration is deprecated and is not availble to be installed on new projects. The following docs are relevant only to projects that already have the integration installed.
 
 </Alert>