Modify example for pinned query (#49481)

I do not see any reason to advertise phones of specific companies.

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

@@ -19,7 +19,7 @@ GET /_search
             "ids" : ["1", "4", "100"],
             "organic" : {
             	"match":{
-            		"description": "iphone"
+            		"description": "brown shoes"
             	}
             }
         }
@@ -33,4 +33,4 @@ GET /_search
 `ids`::
 An array of <<mapping-id-field, document IDs>> listed in the order they are to appear in results.
 `organic`::
-Any choice of query used to rank documents which will be ranked below the "pinned" document ids.
+Any choice of query used to rank documents which will be ranked below the "pinned" document ids.