Improve documentation of generated classes.

Motivation:

- Improve documentation to include references for idiomatic gRPC/IO client and server APIs.
- Provide clear comparisons between high-level and low-level APIs for clarity.

Changes:

- Updated `ioclient.adoc` and `ioserver.adoc` with new sections for idiomatic gRPC/IO APIs.
- Added detailed descriptions and tables in `plugin.adoc` to explain generated RPC files and their purposes.
- Added anchors for client and server request/response API sections (`client-request-response-api`, `server-request-response-api`).

Author: zZHorizonZz

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

@@ -199,6 +199,7 @@ Flowable<String> responseStream = client
 
 NOTE: this requires RxJava version of GrpcClient
 
+[[client-request-response-api]]
 === Client request/response API
 
 The gRPC request/response client API provides an alternative way to interact with a server without the need of a generated stub.

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

@@ -51,6 +51,7 @@ Deadline are cascaded, e.g. when the current `io.grpc.Context` carries a deadlin
 set, the client automatically inherits the implicit deadline. Such deadline can be set when using a stub within a gRPC server
 call.
 
+[[idiomatic-client-io]]
 === Idiomatic gRPC/IO client
 
 The <<vertx-grpc-protoc-plugin,Vert.x gRPC protoc plugin>> supports the generation of gRPC/IO client code:

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

@@ -42,6 +42,7 @@ The Vert.x gRPC Server can bridge a gRPC service to use with _grpc-java_ generat
 
 The bridge supports deadline automatic cancellation: when a gRPC request carrying a timeout is received, a deadline is associated with the `io.grpc.Context` an can be obtained from the current context. This deadline automatically cancels the request in progress when its associated timeout fires.
 
+[[idiomatic-server-io]]
 === Idiomatic gRPC/IO service
 
 The <<vertx-grpc-protoc-plugin,Vert.x gRPC protoc plugin>> supports the generation of gRPC/IO client code:

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

@@ -213,10 +213,42 @@ NOTE: the generator plugin is tech preview and can be subject to changes
 
 === Generated RPC files
 
-For each service definition, the plugin creates several Java RPC files, let's have a quick look at them:
+For each service definition (e.g., `Greeter`), the plugin creates several Java RPC files with specific purposes:
 
-- `examples/Greeter.java`
-- `examples/GreeterClient.java`
-- `examples/GreeterService.java`
-- `examples/GreeterGrpcClient.java`
-- `examples/GreeterGrpcService.java`
+[cols="2,4,1", options="header"]
+|===
+|Generated File |Description |Details
+
+|`Greeter.java`
+|Base interface defining the service contract with all RPC methods declared as abstract methods
+|Common to both client and server
+
+|`GreeterClient.java`
+|High-level client interface with idiomatic Vert.x Future-based methods for calling the service
+|<<idiomatic-client,Client API>>
+
+|`GreeterService.java`
+|High-level server interface for implementing the service with idiomatic Vert.x Future-based handlers
+|<<idiomatic-server,Server Stub>>
+
+|`GreeterGrpcClient.java`
+|Low-level client implementation providing direct access to gRPC request/response streams
+|<<client-request-response-api,Client Request/Response API>>
+
+|`GreeterGrpcService.java`
+|Low-level server implementation providing direct access to gRPC request/response streams for handling
+|<<server-request-response-api,Server Request/Response API>>
+|===
+
+NOTE: The `GreeterGrpcClient` and `GreeterGrpcService` classes provide lower-level APIs that give you more control over streaming and flow control, while `GreeterClient` and `GreeterService` provide higher-level, more idiomatic Vert.x APIs that are easier to use for most cases.
+
+Additionally, when `grpc-io=true` is enabled, the plugin generates:
+
+[cols="2,4,1", options="header"]
+|===
+|Generated File |Description |Details
+
+|`GreeterGrpcIo.java`
+|Compatibility layer for using the service with standard `io.grpc` stubs and existing gRPC/IO ecosystem
+|<<idiomatic-server-io,gRPC/IO Server>> / <<idiomatic-client-io,gRPC/IO Client>>
+|===

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

@@ -155,6 +155,7 @@ or you can process a `WriteStream`:
 {@link examples.GrpcServerExamples#streamingResponseStub2}
 ----
 
+[[server-request-response-api]]
 === Server request/response API
 
 The gRPC request/response server API provides an alternative way to interact with a client without the need of extending