[DOCS] Reformat `parent_id` query docs (#44449)

docs/reference/query-dsl/parent-id-query.asciidoc

@@ -4,68 +4,113 @@
 <titleabbrev>Parent ID</titleabbrev>
 ++++
 
-The `parent_id` query can be used to find child documents which belong to a particular parent.
-Given the following mapping definition:
+Returns child documents <<parent-join,joined>> to a specific parent document.
+You can use a <<parent-join,join>> field mapping to create parent-child
+relationships between documents in the same index.
 
+[[parent-id-query-ex-request]]
+==== Example request
+
+[[parent-id-index-setup]]
+===== Index setup
+To use the `parent_id` query, your index must include a <<parent-join,join>>
+field mapping. To see how you can set up an index for the `parent_id` query, try
+the following example.
+
+. Create an index with a <<parent-join,join>> field mapping.
++
+--
 [source,js]
---------------------------------------------
-PUT my_index
+----
+PUT /my-index
 {
-  "mappings": {
-    "properties": {
-      "my_join_field": {
-        "type": "join",
-        "relations": {
-          "my_parent": "my_child"
+    "mappings": {
+        "properties" : {
+            "my-join-field" : {
+                "type" : "join",
+                "relations": {
+                    "my-parent": "my-child"
+                }
+            }
         }
-      }
     }
-  }
 }
 
-PUT my_index/_doc/1?refresh
+----
+// CONSOLE
+// TESTSETUP
+--
+
+. Index a parent document with an ID of `1`.
++
+--
+[source,js]
+----
+PUT /my-index/_doc/1?refresh
 {
-  "text": "This is a parent document",
-  "my_join_field": "my_parent"
+  "text": "This is a parent document.",
+  "my-join-field": "my-parent"
 }
+----
+// CONSOLE
+--
 
-PUT my_index/_doc/2?routing=1&refresh
+. Index a child document of the parent document.
++
+--
+[source,js]
+----
+PUT /my-index/_doc/2?routing=1&refresh
 {
-  "text": "This is a child document",
+  "text": "This is a child document.",
   "my_join_field": {
-    "name": "my_child",
+    "name": "my-child",
     "parent": "1"
   }
 }
-
---------------------------------------------
+----
 // CONSOLE
-// TESTSETUP
+--
+
+[[parent-id-query-ex-query]]
+===== Example query
+
+The following search returns child documents for a parent document with an ID of
+`1`.
 
 [source,js]
---------------------------------------------------
-GET /my_index/_search
+----
+GET /my-index/_search
 {
   "query": {
-    "parent_id": {
-      "type": "my_child",
-      "id": "1"
-    }
+      "parent_id": {
+          "type": "my-child",
+          "id": "1"
+      }
   }
 }
---------------------------------------------------
+----
 // CONSOLE
 
+[[parent-id-top-level-params]]
+==== Top-level parameters for `parent_id`
+
+`type`::
+(Required, string) Name of the child relationship mapped for the
+<<parent-join,join>> field.
 
-==== Parameters
+`id`::
+(Required, string) ID of the parent document. The query will return child
+documents of this parent document.
 
-This query has two required parameters:
+`ignore_unmapped`::
++
+--
+(Optional, boolean) Indicates whether to ignore an unmapped `type` and not
+return any documents instead of an error. Defaults to `false`.
 
-[horizontal]
-`type`::  The **child** type name, as specified in the <<parent-join,`join` field>>.
-`id`::    The ID of the parent document.
+If `false`, {es} returns an error if the `type` is unmapped.
 
-`ignore_unmapped`::  When set to `true` this will ignore an unmapped `type` and will not match any
-documents for this query. This can be useful when querying multiple indexes
-which might have different mappings. When set to `false` (the default value)
-the query will throw an exception if the `type` is not mapped.
+You can use this parameter to query multiple indices that may not contain the
+`type`.
+--