Update README

Author: JalonWong

Cargo.toml

@@ -9,7 +9,7 @@
     name = "stm32f1-hal"
     readme = "README.md"
     repository = "https://github.com/mcu-rust/stm32f1-hal"
-    version = "0.3.0"
+    version = "0.3.1"
 
     [package.metadata.docs.rs]
         features = ["stm32f103", "xG"]

README.md

@@ -2,7 +2,14 @@
 Because the design of [stm32f1xx-hal](https://github.com/stm32-rs/stm32f1xx-hal) is unsuitable for my needs and [stm32-hal](https://github.com/David-OConnor/stm32-hal) doesn't support the F1 series, I decided to write a new crate.
 Many codes come from [stm32f1xx-hal](https://github.com/stm32-rs/stm32f1xx-hal).
 
-Example is [here](https://github.com/mcu-rust/stm32f1-hal/blob/main/examples/f103c8/src/main.rs).
+See [example](examples/f103c8/src/main.rs).
+
+## Usage
+```shell
+cargo add stm32f1-hal
+```
+
+See [crate](https://crates.io/crates/stm32f1-hal).
 
 ## Design
 Below are the design principles.