Fix typo in Asciidoctor attributes configuration
Closes
@@ -304,7 +304,7 @@ found in the following array:
You can use `\*` as a wildcard to match fields with different names. For example,
`users.*.role` could be used to document the role of every user in the following JSON:
-[source,json.indent=0]
+[source,json,indent=0]
----
{
"users":{
