feat: udpate readme

README.md

@@ -13,3 +13,17 @@ Calling Rust FFI libraries from Go
 ```shell
 cargo install cargo-zigbuild
 ```
+
+
+# Build
+
+Build or Cross build
+
+```shell
+just build
+```
+
+```shell
+just build-linux-x86
+```
+

justfile

@@ -1,6 +1,9 @@
 _:
   @just --list
 
+build:
+  cargo build
+
 build-linux-x86:
   #rustup target add x86_64-unknown-linux-gnu
   cargo zigbuild --release --target=x86_64-unknown-linux-gnu