provide examples

examples/simple_tree.rs

@@ -0,0 +1,28 @@
+//! Implements this tree
+//! ```
+//! 1
+//! ├── 2
+//! └── 3
+//!     ├── 4
+//!     └── 5
+//! ```
+
+use ego_tree::{tree, NodeMut, Tree};
+
+fn main() {
+    // Manual construction of the tree
+    let mut tree: Tree<i32> = Tree::new(1);
+    let mut root: NodeMut<i32> = tree.root_mut();
+    root.append(2);
+    let mut child: NodeMut<i32> = root.append(3);
+    child.append(4);
+    child.append(5);
+    println!("Manual:\n{tree}");
+
+    // Construction of the tree through the tree! macro
+    let macro_tree: Tree<i32> = tree!(1 => {2, 3 => {4, 5}});
+    println!("Automated:\n{macro_tree}");
+
+    // Prooving equality
+    assert_eq!(tree, macro_tree);
+}