[DOCS] Fix anchor for 7.12 deprecations

Author: jrodewig

docs/reference/migration/migrate_7_12.asciidoc

@@ -91,7 +91,7 @@ SSL/TLS versions on your JDK].
 //end::notable-breaking-changes[]
 
 [discrete]
-[[deprecated-7.11]]
+[[deprecated-7.12]]
 === Deprecations
 
 The following functionality has been deprecated in {es} 7.12