[DOCS] delete index no longer supports specifying aliases

docs/reference/indices/delete-index.asciidoc

@@ -10,10 +10,12 @@ DELETE /twitter
 // CONSOLE
 // TEST[setup:twitter]
 
-The above example deletes an index called `twitter`. Specifying an index,
-alias or wildcard expression is required.
+The above example deletes an index called `twitter`. Specifying an index or a
+wildcard expression is required. Aliases cannot be used to delete an index.
+Wildcard expressions are resolved to matching concrete indices only.
 
-The delete index API can also be applied to more than one index, by either using a comma separated list, or on all indices (be careful!) by using `_all` or `*` as index.
+The delete index API can also be applied to more than one index, by either
+using a comma separated list, or on all indices (be careful!) by using `_all` or `*` as index.
 
 In order to disable allowing to delete indices via wildcards or `_all`,
 set `action.destructive_requires_name` setting in the config to `true`.