Add d2 to export format options

Author: goto1134

src/main/java/com/structurizr/cli/export/ExportCommand.java

@@ -71,7 +71,7 @@ public void run(String... args) throws Exception {
         option.setRequired(true);
         options.addOption(option);
 
-        option = new Option("f", "format", true, String.format("Export format: %s[/%s|%s]|%s|%s|%s|%s|%s|%s|%s|%s", PLANTUML_FORMAT, PLANTUML_STRUCTURIZR_SUBFORMAT, PLANTUML_C4PLANTUML_SUBFORMAT, WEBSEQUENCEDIAGRAMS_FORMAT, MERMAID_FORMAT, DOT_FORMAT, ILOGRAPH_FORMAT, JSON_FORMAT, THEME_FORMAT, STATIC_FORMAT, CUSTOM_FORMAT));
+        option = new Option("f", "format", true, String.format("Export format: %s[/%s|%s]|%s|%s|%s|%s|%s|%s|%s|%s|%s", PLANTUML_FORMAT, PLANTUML_STRUCTURIZR_SUBFORMAT, PLANTUML_C4PLANTUML_SUBFORMAT, WEBSEQUENCEDIAGRAMS_FORMAT, MERMAID_FORMAT, DOT_FORMAT, ILOGRAPH_FORMAT, D2_FORMAT, JSON_FORMAT, THEME_FORMAT, STATIC_FORMAT, CUSTOM_FORMAT));
         option.setRequired(true);
         options.addOption(option);