Expand plugin argument documentation with detailed value specifications

Author: zZHorizonZz

vertx-grpc-docs/src/main/asciidoc/plugin.adoc

@@ -159,14 +159,15 @@ By default, the plugin generates both client and service files. If you need only
 
 === Arguments:
 
-- _[--]grpc-client_: generate the client files
-- _[--]grpc-service_: generate the service files
-- _[--]grpc-io_: generate stub files compatible with `io.grpc:grpc-stub`, not generated by default. When using this option, you must also ensure the grpc-java plugin is configured (as shown in the Maven configuration above)
-- _[--]grpc-transcoding_: whether to generate transcoding options for methods with HTTP annotations
-- _[--]vertx-codegen_: whether to add Vert.x annotations to the generated classes (`@VertxGen`) By default, this is disabled
-- _[--]service-prefix_: generate service classes with a prefix. For example, if you set it to `MyService`, the generated service class will be `MyServiceGreeterService` instead of `GreeterService`.
+- _[--]grpc-client[=true/false]_: generate the client files
+- _[--]grpc-service[=true/false]_: generate the service files
+- _[--]grpc-io[=true/false]_: generate stub files compatible with `io.grpc:grpc-stub`, not generated by default. When using this option, you must also ensure the grpc-java plugin is configured (as shown in the Maven configuration above)
+- _[--]grpc-transcoding[=true/false]_: whether to generate transcoding options for methods with HTTP annotations
+- _[--]vertx-codegen[=true/false]_: whether to add Vert.x annotations to the generated classes (`@VertxGen`) By default, this is disabled
+- _[--]service-prefix[=Your Name]_: generate service classes with a prefix. For example, if you set it to `MyService`, the generated service class will be `MyServiceGreeterService` instead of `GreeterService`.
 
 * [--] This means the argument can be prefixed with `--` when used as JVM arguments, but should be used without `--` when specified in the options tag. If possible, users should use plugin options as a more universal protoc plugin approach.
+* [=value] This means the argument can optionally specify a value. For boolean arguments (true/false), if no value is specified, the default is `true` when the argument is present. For string arguments like `service-prefix`, a value must be provided.
 
 If no specific generation options are provided, both client and service files will be generated by default. By default, all extensions (currently only 'http') are supported.