Feat: Create simple grep function.

src/main.rs

@@ -10,5 +10,11 @@ struct Cli {
 fn main() {
     let args = Cli::parse();
 
-    println!("pattern: {:?}, path: {:?}", args.pattern, args.path)
+    let content = std::fs::read_to_string(&args.path).expect("Could not read file.");
+
+    for line in content.lines() {
+        if line.contains(&args.pattern) {
+            println!("{}", line)
+        }
+    }
 }