Write up README.md

README.md

@@ -4,9 +4,31 @@
 [![Docs](https://docs.rs/tiny_bail/badge.svg)](https://docs.rs/tiny_bail/latest/tiny_bail/)
 [![License](https://img.shields.io/badge/license-MIT%2FApache-blue.svg)](https://github.com/benfrankel/tiny_bail)
 
-TODO: Sample code.
+This crate provides four failure-skipping macros: `r!`, `rq!`, `c!`, and `cq!`; along with their long-form aliases
+`or_return!`, `or_return_quiet!`, `or_continue!`, and `or_continue_quiet!`, respectively.
+
+The macros support handle both `Option` and `Result` types out-of-the-box. This can be extended by implementing the
+`Success` trait for other types.
+
+You can provide a return value as an optional first argument to the macro, or you can omit it to default to
+`Default::default()`—which also works in functions with no return value.
+
+# Example
 
 ```rust
+/// Increment the last number of a list, or warn if it's empty.
+fn increment_last(list: &mut [usize]) {
+    // With `r!`:
+    *r!(list.last_mut()) += 1;
+
+    // Without `r!`:
+    if let Some(x) = list.last_mut() {
+        *x += 1;
+    } else {
+        warn!("Empty list");
+        return;
+    }
+}
 ```
 
 # License