Add very basic docs

src/lib.rs

@@ -1,3 +1,30 @@
+//! Usage example:
+//! ```rust
+//! use ferrite_lua::{compile, vm};
+//!
+//! #[derive(Debug, PartialEq, Eq)]
+//! pub struct Print;
+//! impl vm::RustFunction for Print {
+//!     fn execute(&self, parameters: Vec<vm::Value>) -> Result<Vec<vm::Value>, vm::RuntimeError> {
+//!         println!("{:?}", parameters);
+//!         Ok(Vec::new())
+//!     }
+//!
+//!     fn as_indexable(&self) -> String {
+//!         "std::print".to_owned()
+//!     }
+//! }
+//!
+//! let compilation_unit = compile("print(\"hello\")", None).unwrap();
+//!
+//! let mut vm = vm::VirtualMachine::default();
+//! vm.set_global("print".into(), Print.into());
+//!
+//! let mut runner = compilation_unit.with_virtual_machine(&mut vm).execute();
+//!
+//! while runner.next().unwrap().is_none() { }
+//! ```
+
 use std::{fmt::Debug, path::PathBuf};
 
 use thiserror::Error;

src/vm.rs

@@ -554,7 +554,7 @@ pub struct ClosureRunner {
 }
 
 #[derive(Clone, Debug)]
-pub enum StackValue {
+enum StackValue {
     Value(Value),
     Ref(Rc<RefCell<Value>>),
 }