Refactor update_libchdb.sh for system-wide install and improve README documentation

Author: JakkuSakura

.gitignore

@@ -2,7 +2,7 @@
 Cargo.lock
 *.tar.gz
 *.so
-*.h
+chdb.h
 var
 udf
 *.parquet

README.md

@@ -3,21 +3,42 @@
 [![Rust](https://github.com/chdb-io/chdb-rust/actions/workflows/rust.yml/badge.svg)](https://github.com/chdb-io/chdb-rust/actions/workflows/rust.yml)
 
 # chdb-rust <img src="https://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/Rust_programming_language_black_logo.svg/1024px-Rust_programming_language_black_logo.svg.png" height=20 />
+
 Experimental [chDB](https://github.com/chdb-io/chdb) FFI bindings for Rust
 
-### Status
+## Status
 
 - Experimental, unstable, subject to changes
-- Requires [`libchdb`](https://github.com/chdb-io/chdb) on the system
+- Requires [`libchdb`](https://github.com/chdb-io/chdb) on the system. You can install the compatible version from
+  `install_libchdb.sh`
+
+## Usage
+
+### Install libchdb
+
+You can install it system-wide
+
+```bash
+./update_libchdb.sh --global
+```
+
+or use it in a local directory
+
+```bash
+./update_libchdb.sh --local
+```
+
+### Build
 
-#### Build binding
 ```bash
-./update_libchdb.sh
 RUST_BACKTRACE=full cargo build --verbose
+
 ```
 
 ### Run tests
+
 `cargo test`
 
 ### Examples
+
 See `tests` directory.

build.rs

@@ -16,7 +16,7 @@ fn main() {
     let bindings = bindgen::Builder::default()
         // The input header we would like to generate
         // bindings for.
-        .header("chdb.h")
+        .header("wrapper.h")
         // Tell cargo to invalidate the built crate whenever any of the
         // included header files changed.
         .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))