docs: update README

README.md

@@ -1,2 +1,37 @@
 # define-emitter-composable
 Creates a Vue composable function for providing or injecting a mitt event emitter.
+
+## Install
+```bash
+$ npm install define-emitter-composable
+```
+
+```js
+import defineEmitterComposable from 'define-emitter-composable'
+```
+
+## Usage
+```js
+// Creates a composable function for providing or injecting a mitt event emitter.
+const useFooEmitter = defineEmitterComposable<{ bar: string, baz: number }>({ key: Symbol('bar') , throwOnNoProvider: () => new Error('No provider for bar') })
+const useBarEmitter = defineEmitterComposable()
+
+// In a Vue component setup
+setup() {
+  const fooEmitter = useFooEmitter('provide') // Provides an emitter
+  fooEmitter.on('bar', (payload) => {
+    // Handle the event
+  })
+
+  // Or inject an existing event emitter
+  const injectedBarEmitter = useFooEmitter() // Or `useFooEmitter('inject')`
+  injectedFooEmitter.emit('bar', 'bar')
+  injectedFooEmitter.emit('baz', 123)
+
+  // If `injectDefault` or `throwOnNoProvider` options are not set, the return value may be undefined
+  const undefinedEmitter = useBarEmitter() // undefined
+}
+```
+
+## License
+[MIT](./LICENSE)