add rectangles mini project base with cargo init

Author: Syaw0

projects/rectangles/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "rectangles"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

projects/rectangles/src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("Hello, world!");
+}