feat(doc): add readme of usage

README.md

@@ -1 +1,29 @@
-# taitank-safe
+# Taitank Safe
+
+(In Progress) Rust binding of [tencent/taitank](https:://github.com/tencent/taitank) provides safe binding to the Taitank Layout Library.
+
+## Usage
+
+```toml
+[dependencies]
+taitank_safe = "0.0.1"
+```
+
+```rust
+use taitank_safe::*;
+
+let mut root = node_create();
+set_width(&mut root, 100.0);
+set_height(&mut root, 100.0);
+
+let mut root_child0 = node_create();
+set_flex_grow(&mut root_child0, 1.0);
+set_flex_basis(&mut root_child0, 50.0);
+insert_child(&mut root, &mut root_child0, 0);
+
+let mut root_child1 = node_create();
+set_flex_grow(&mut root_child1, 1.0);
+insert_child(&mut root, &mut root_child1, 1);
+
+layout!(&mut root);
+```