MultiPartConfig in HTTP Vert.x extension is insufficiently documented

Closes quarkusio#30046

Co-authored-by: Guillaume Smet <[email protected]>

extensions/vertx-http/runtime/src/main/java/io/quarkus/vertx/http/runtime/MultiPartConfig.java

@@ -15,7 +15,12 @@
 public class MultiPartConfig {
 
     /**
-     * A list of {@code ContentType} to indicate whether a given multipart field should be handled as a file part.
+     * A comma-separated list of {@code ContentType} to indicate whether a given multipart field should be handled as a file
+     * part.
+     *
+     * You can use this setting to force HTTP-based extensions to parse a message part as a file based on its content type.
+     *
+     * For now, this setting only works when using RESTEasy Reactive.
      */
     @ConfigItem
     @ConvertWith(TrimmedStringConverter.class)