docs(format): adds a content type to the docs files (strimzi#11922)

Signed-off-by: prmellor <pmellor@redhat.com>

Author: PaulRMellor

crd-generator/src/main/java/io/strimzi/crdgenerator/DocGenerator.java

@@ -530,6 +530,7 @@ public static void main(String[] args) throws IOException, ClassNotFoundExceptio
         ApiVersion crApiVersion = ApiVersion.V1BETA2;
 
         try (OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(out), StandardCharsets.UTF_8)) {
+            writer.append(":_mod-docs-content-type: REFERENCE").append(NL).append(NL);
             writer.append("// This file is auto-generated by ")
                 .append(DocGenerator.class.getName())
                 .append(".").append(NL);