document rust api

README.md

@@ -1 +1,21 @@
 # Demo editor
+
+## Rust api
+
+```rust
+use edit::{edit, EditOptions, TickRange};
+
+fn main() {
+    let options = EditOptions {
+        unlock_pov: true,
+        cut: Some(TickRange {
+            from: 1000.into(),
+            to: 2000.into(),
+        }),
+        ..EditOptions::default()
+    };
+    let input = fs::read("in.demo").unwrap();
+    let output = edit(&input, options);
+    fs::write("out.dem", output).unwrap();
+}
+```