fixed URL for configuring JSON support

Author: andlinger

docs/src/main/asciidoc/writing-extensions.adoc

@@ -1899,7 +1899,7 @@ The Jackson extension will then use the produced build item to register a module
 
 If you need more customization capabilities than registering a module,
 you can produce a CDI bean that implements `io.quarkus.jackson.ObjectMapperCustomizer` via an `AdditionalBeanBuildItem`.
-More info about customizing Jackson can be found on the JSON guide xref:rest-json.adoc#configuring-json-support[Configuring JSON support]
+More info about customizing Jackson can be found on the JSON guide xref:rest-json.adoc#json[Configuring JSON support]
 
 ==== Customizing JSON-B
 First, add an *optional* dependency to `quarkus-jsonb` on your extension's runtime module.