Add readme

Author: richerfu

README.md

@@ -4,4 +4,16 @@ This project allow us to build zig that can build dynamic or use `zig cc` for Op
 
 For now, we use the default logic of `musl` to link libc or other logic. It may has some issues, but we need more examples or projects to test it.
 
-If you find some codes or logic need to adapt, you can submit a new issue or PR. 
+If you find some codes or logic need to adapt, you can submit a new issue or PR. 
+
+## How to build
+
+Apply the git [patch](./patch/zig-patch.patch) to zig's source code and build it.
+
+For example, you can apply it to `zig-bootstrap` the sub-folder named `zig`. And Using zig-bootstrap to build zig with your target.
+
+## Platform
+
+- [x] Macos
+- [ ] Windows
+- [ ] Linux