Added example from readme

examples/temp.rs

@@ -0,0 +1,28 @@
+use unqlite::{UnQLite, KV, Cursor};
+
+fn main() {
+    // The database memory is not handled by Rust, and the database is on-disk,
+    // so `mut` is not neccessary.
+    let unqlite = UnQLite::create_temp();
+    // Use any type that can use as `[u8]`
+    unqlite.kv_store("key", "a long length value").unwrap();
+    unqlite.kv_store("abc", [1,2,3]).unwrap();
+
+    let mut entry = unqlite.first();
+    // Iterate records
+    loop {
+        if entry.is_none() { break; }
+
+        let record = entry.expect("valid entry");
+        let (key, value) = record.key_value();
+        println!("* Go through {:?} --> {:?}", key, value);
+
+        if value.len() > 10 {
+            println!("** Delete key {:?} by value length", key);
+            entry = record.delete();
+        } else {
+            entry = record.next();
+        }
+    }
+
+}