add sled

sled/src/main.rs

@@ -0,0 +1,18 @@
+fn main() -> Result<(), Box<dyn std::error::Error>>{
+    let path = "a.file";
+    let tree = sled::open(path)?;
+
+    let k = "hello";
+    let v = "world";
+
+    // insert and get, similar to std's BTreeMap
+    tree.insert(k, v)?;
+
+    for kv in tree.range(k..) {
+        println!("kv: {:?}", kv);
+    }
+
+    tree.flush()?;
+
+    Ok(())
+}