Clarify that the keystore obfuscates secrets only. (#38667) (#38888)

(cherry picked from commit 7648a2a)

Co-authored-by: Craig MacKenzie <[email protected]>

libbeat/docs/keystore.asciidoc

@@ -18,7 +18,7 @@
 
 When you configure {beatname_uc}, you might need to specify sensitive settings,
 such as passwords. Rather than relying on file system permissions to protect
-these values, you can use the {beatname_uc} keystore to securely store secret
+these values, you can use the {beatname_uc} keystore to obfuscate stored secret
 values for use in configuration settings.
 
 After adding a key and its secret value to the keystore, you can use the key in