docs: add integration and usage guide in readme (#33)

* docs(readme): add integration section

* docs(readme): add example usages section

README.md

@@ -6,6 +6,46 @@ The `SetupGo.cmake` is a CMake module containing a `setup_go` function.
 This function sets up a specific version of Go to be used in a CMake project.
 It downloads a specific Go build based on the current operating system and architecture from the official Go website and extracts the downloaded result to the CMake build directory.
 
+## Integration
+
+This module can be integrated into a CMake project in the following ways:
+
+- Manually download the [`SetupGo.cmake`](./cmake/SetupGo.cmake) file and include it in the CMake project:
+  ```cmake
+  include("path/to/SetupGo.cmake")
+  ```
+- Use [`file(DOWNLOAD)`](https://cmake.org/cmake/help/latest/command/file.html#download) to automatically download the `SetupGo.cmake` file:
+  ```cmake
+  file(
+    DOWNLOAD "https://threeal.github.io/setup-go-cmake/v1.0.0"
+    "${CMAKE_BINARY_DIR}/SetupGo.cmake"
+  )
+  include("${CMAKE_BINARY_DIR}/SetupGo.cmake")
+  ```
+- Use [CPM.cmake](https://github.com/cpm-cmake/CPM.cmake) to add this package to the CMake project:
+  ```cmake
+  cpmaddpackage("gh:threeal/setup-go-cmake@1.0.0")
+  include("${SetupGo_SOURCE_DIR}/cmake/SetupGo.cmake")
+  ```
+
+## Example Usages
+
+This example demonstrates how to set up the latest version of Go to be used in a CMake project:
+
+```cmake
+setup_go()
+
+execute_process(COMMAND ${GO_EXECUTABLE} version)
+```
+
+### Specify Go Version
+
+Use the `VERSION` argument to specify the Go version to set up:
+
+```cmake
+setup_go(VERSION 1.21.9)
+```
+
 ## License
 
 This project is licensed under the terms of the [MIT License](./LICENSE).