Update parameter docs to better match Elastic API Reference template

Author: jrodewig

docs/reference/query-dsl/prefix-query.asciidoc

@@ -26,14 +26,15 @@ GET /_search
 
 [[prefix-query-top-level-params]]
 ==== Top-level parameters for `term`
-`<field>`::
-Field you wish to search.
+`<field>` (Required)::
+(string) Field you wish to search.
 
 [[prefix-query-field-params]]
 ==== Parameters for `<field>`
-`value`::
-Beginning characters of terms you wish to find in the provided `<field>`.
+`value` (Required)::
+(string) Beginning characters of terms you wish to find in the provided
+`<field>`.
 
-`rewrite` (Expert)::
-Method used to rewrite the query. For valid values and more information, see the
-<<query-dsl-multi-term-rewrite, `rewrite` parameter>>. Optional.
+`rewrite` (Optional)::
+(string) Method used to rewrite the query. For valid values and more
+information, see the <<query-dsl-multi-term-rewrite, `rewrite` parameter>>.