[ProtobufQuick][GrpcQuick] add documentation examples for QML-argument

- qt-add-protobuf and qt-add-grpc APIs take "QML" as a parameter,
which requires ProtobufQuick and GrpcQuick supplied to find_package
call, but it's not mentioned in documentation.

Pick-to: 6.8 6.9
Task-number: QTBUG-131780
Change-Id: I26c24e0c2695587056e46782cb4bb36438c46313
Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>

src/grpc/doc/src/qt-add-grpc.qdoc

@@ -78,7 +78,25 @@ target to the protobuf one:
 \list
     \include qtprotoccommon.qdocinc proto_files-li
     \include qtprotoccommon.qdocinc proto_includes-li
-    \include qtgrpcgen.qdocinc qml-li
+    \li \c {QML} generates the QML client API for the \gRPC service.
+        The argument requires the \c GrpcQuick Qt component.
+        \badcode
+            find_package(Qt6 6.8 REQUIRED COMPONENTS Quick Protobuf ProtobufQuick Grpc GrpcQuick)
+            ...
+            # Generate the protobuf types
+            qt_add_protobuf(test_service_client
+                PROTO_FILES
+                    test_service.protobuf
+                QML
+            )
+            ...
+            # Generate \gRPC client functionality
+            qt_add_grpc(test_service_client CLIENT
+                PROTO_FILES
+                    test_service.protobuf
+                QML
+            )
+        \endcode
     \include qtprotoccommon.qdocinc output_directory-li
     \include qtprotoccommon.qdocinc generate_package_subfolders-li
     \include qtprotoccommon.qdocinc copy_comments-li

src/protobuf/doc/src/qt-add-protobuf-example.qdocinc

@@ -41,7 +41,7 @@ to the \c{MyMessages} library.
 cmake_minimum_required(VERSION 3.16...3.22)
 project(MyThings)
 
-find_package(Qt6 REQUIRED COMPONENTS Protobuf Quick)
+find_package(Qt6 REQUIRED COMPONENTS Protobuf ProtobufQuick Quick)
 qt_standard_project_setup()
 
 qt_add_protobuf(MyMessagesPlugin

src/protobuf/doc/src/qt-add-protobuf.qdoc

@@ -46,6 +46,8 @@ link.
         module, a new QML module will be created implicitly.
 
         \badcode
+            find_package(Qt6 6.8 REQUIRED COMPONENTS Quick Protobuf ProtobufQuick)
+            ...
             qt_add_executable(target
                 ...
             )
@@ -60,6 +62,8 @@ link.
         attach the generated protobuf types to that module.
 
         \badcode
+            find_package(Qt6 6.8 REQUIRED COMPONENTS Quick Protobuf ProtobufQuick)
+            ...
             qt_add_qml_module(target
                 ...
             )
@@ -70,6 +74,9 @@ link.
             )
         \endcode
 
+        \note If you use QML argument, you have to add ProtobufQuick into
+              find_package call. See examples above.
+
     \li \c {QML_URI}
         defines the \c URI used for the QML module.