Add basic example

examples/basic.rs

@@ -0,0 +1,16 @@
+fn main() {
+    let some_content = "Something";
+    let compression_level = 3;
+
+    // Compress some text
+    let compressed =
+        zstd::encode_all(some_content.as_bytes(), compression_level).unwrap();
+
+    // Now uncompress it
+    let decoded: Vec<u8> = zstd::decode_all(compressed.as_slice()).unwrap();
+
+    // Convert it to text
+    let decoded_text = std::str::from_utf8(&decoded).unwrap();
+
+    assert_eq!(some_content, decoded_text);
+}