Better README and fix type

Author: flamingelk

README.md

@@ -3,3 +3,13 @@
 RichResultField is a text field that can be overlaid with a similar-looking box containing arbitrary text. Useful if you want to save a particular value from a picker but display something more friendly from the user.
 
 Requires Bootstrap.
+
+Example usage:
+
+```aiignore
+import RichResultField from '@universityofwarwick/rich-result-field';
+
+const input = document.getElementById('input');
+const richResultField = new RichResultField(input);
+richResultField.store('input-value', 'Disaplay text');
+```

lib/rich-result-field.d.ts

@@ -7,7 +7,7 @@
  */
 export default class RichResultField {
     $input: JQuery<HTMLElement>;
-    $uneditables: JQuery<HTMLElement>;
+    $uneditable: JQuery<HTMLElement>;
     constructor(input: HTMLElement);
     /** Clear field, focus for typing */
     edit(): void;