[Docs] Specify field types not supporting doc values (elastic#49041)

The `string` type (with option `analyzed`) has been replaced by `text` after `6.0`, 
also the `annonated_text` field do not support doc values and should be mentioned.

Author: antoinewg

docs/reference/mapping/params/doc-values.asciidoc

@@ -15,7 +15,7 @@ Doc values are the on-disk data structure, built at document index time, which
 makes this data access pattern possible. They store the same values as the
 `_source` but in a column-oriented fashion that is way more efficient for
 sorting and aggregations. Doc values are supported on almost all field types,
-with the __notable exception of `analyzed` string fields__.
+with the __notable exception of `text` and `annotated_text` fields__.
 
 All fields which support doc values have them enabled by default. If you are
 sure that you don't need to sort or aggregate on a field, or access the field