구조적 변경: README.md 파일 추가 및 초기 설정 안내

- SOLAPI SDK for Rust에 대한 설명을 포함한 README.md 파일 새로 추가: 패키지 설치 방법, 사용법, 이슈 제기 방법 및 라이센스 정보 제공.
- 사용자에게 필요한 정보를 명확히 전달하여 SDK 사용을 용이하게 함.

Author: Palbahngmiyine

README.md

@@ -0,0 +1,35 @@
+# SOLAPI SDK for Rust
+
+You can send text messages(SMS, LMS, MMS), Kakao Alimtalk in Korea using this
+package.
+This package is 100% compatible with SOLAPI family services (CoolSMS and etc..).
+
+## Installing
+
+Add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+solapi = "0.1.0"
+```
+
+Or use the `cargo add` command:
+
+```bash
+cargo add solapi
+```
+
+## Usage
+
+See [examples folders](https://github.com/solapi/solapi-rust/tree/master/examples)
+
+## Opening Issues
+
+If you've encountered a bug with the SOLAPI SDK for Rust, we'd love to hear about it.  
+Before opening a new issue, please check the [existing issues](https://github.com/solapi/solapi-rust/issues) to see if your problem has already been reported.  
+It's helpful to include the SDK version, your Rust version, and the OS you're using.  
+If applicable, please also provide a stack trace and a minimal reproducible example.
+
+## License
+
+Licensed under the MIT License.