update README

README.md

@@ -2,6 +2,8 @@
 
 # gobang
 
+gobang is currently in alpha
+
 A cross-platform terminal database tool written in Rust
 
 [![github workflow status](https://img.shields.io/github/workflow/status/TaKO8Ki/gobang/CI/main)](https://github.com/TaKO8Ki/gobang/actions) [![crates](https://img.shields.io/crates/v/gobang.svg?logo=rust)](https://crates.io/crates/gobang)
@@ -15,3 +17,14 @@ A cross-platform terminal database tool written in Rust
 - Cross-platform support (macOS, Windows, Linux)
 - Multiple Database support (MySQL PostgreSQL, SQLite)
 - Intuitive keyboard only control
+
+## Installation
+
+### Cargo
+
+If you already have a Rust environment set up, you can use the `cargo install` command:
+
+```
+$ cargo install --version 0.1.0-alpha.0 gobang
+```
+