Update README.

Author: jmjoy

README.md

@@ -4,4 +4,19 @@ A library that allows us to write PHP extensions in pure Rust, using safe Rust w
 
 (一个让我们可以用纯Rust写PHP扩展的库，并且尽可能使用safe Rust，同时也是一个PHP的Binding库。)
 
-***Now the peojct is still under development.***
+***Now the peojct is still under development.***
+
+## Usage
+
+First you have to install `cargo-generate`:
+
+```bash
+cargo install cargo-generate
+```
+
+Then create a PHP extension project from template:
+
+```bash
+cargo generate --git https://github.com/jmjoy/phper-ext-skel.git
+```
+