mention that text index can be on-disk

Author: generall

qdrant-landing/content/documentation/concepts/indexing.md

@@ -636,6 +636,8 @@ Payload index on-disk is supported for following types:
 * `float`
 * `datetime`
 * `uuid`
+* `text`
+* `geo`
 
 The list will be extended in future versions.