Optimisations

- Added phpunit cache to .gitignore
- Updated README with latest helper.php example.
- Minor phpDocs changes.

helpers.php

@@ -47,7 +47,7 @@ function request(): Request
 /**
  * Get input class
  * @param string|null $index Parameter index name
- * @param string|null $defaultValue Default return value
+ * @param string|mixed|null $defaultValue Default return value
  * @param array ...$methods Default methods
  * @return \Pecee\Http\Input\InputHandler|array|string|null
  */