Update README.md

Fix minor typo

README.md

@@ -7,7 +7,7 @@
 [![Rate on Openbase](https://badges.openbase.io/js/rating/@ericblade/quagga2.svg)](https://openbase.io/js/@ericblade/quagga2?utm_source=embedded&utm_medium=badge&utm_campaign=rate-badge)
 
 This is a fork of the original QuaggaJS library, that will be maintained until such time as the
-original author and maintainer returns, or it has been completely replaced by built-in browser and
+original author and maintainer returns, or it has been completely replaced by a built-in browser and
 node functionality.
 
 - [Changelog](https://github.com/ericblade/quagga2/releases)