feat: add --version

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "json_env"
-version = "1.0.7"
+version = "1.1.0"
 edition = "2021"
 license = "Apache-2.0"
 description ="`json_env` loads an environment variables from a file called `.env.json` in the current directory and starts a subprocess with them."

src/main.rs

@@ -5,22 +5,31 @@ use std::fs::File;
 use std::io::Read;
 use std::process::Command;
 
+
+const VERSION: &str = env!("CARGO_PKG_VERSION");
+
 // `json_env` is [dotenv](https://github.com/motdotla/dotenv), but with JSON.
 // See [readme](Readme.md) for more information.
 fn main() {
     let args: Vec<String> = env::args().collect();
     let help_text = concat!("json_env reads the .env.json file in the current directory and runs a program with these environment variables.\n",
     "Usage:",
     "json_env <executable> <options for executable>\n",
-    "json_env itself has no config options"
+    "json_env itself has no config options."
     );
 
     if args.len() < 2 {
         println!("{}", help_text);
     }
 
     if args[1] == "--help" {
-        println!("{}", help_text)
+        println!("{}", help_text);
+        return;
+    }
+
+    if args[1] == "--version" {
+        println!("json_env version {}", VERSION);
+        return;
     }
 
     match File::open(".env.json") {