[DOCS] Fix Context Suggester deprecated macro for Asciidoctor (#42407)

Author: jrodewig

docs/reference/search/suggesters/context-suggest.asciidoc

@@ -13,8 +13,13 @@ Every context mapping has a unique name and a type. There are two types: `catego
 and `geo`. Context mappings are configured under the `contexts` parameter in
 the field mapping.
 
+ifdef::asciidoctor[]
+deprecated:[6.4.0, "Indexing and querying without context on a context enabled completion field is deprecated and will be removed in the next major release."]
+endif::[]
+ifndef::asciidoctor[]
 deprecated[6.4.0, Indexing and querying without context on a context enabled completion
 field is deprecated and will be removed in the next major release.]
+endif::[]
 
 The following defines types, each with two context mappings for a completion
 field: