Add example project.

CMakeLists.txt

@@ -0,0 +1,12 @@
+cmake_minimum_required(VERSION 3.5)
+
+project(hello-world-qt VERSION 1.0)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+find_package(Qt6 COMPONENTS Widgets REQUIRED)
+
+add_executable(hello-world-qt main.cpp)
+
+target_link_libraries(hello-world-qt PRIVATE Qt6::Widgets)