Update README.md

Author: pronskiy

README.md

@@ -1,6 +1,6 @@
 # Phpup: the PHP toolchain
 
-_Phpup_ is a one-file binary with _**zero dependencies**_ that includes Composer and other PHP tools. It also allows to install a per-project PHP based on your `composer.json`.
+_Phpup_ is a single-file binary with _**zero dependencies**_ that includes Composer and other PHP tools. It also allows to install a per-project PHP based on your `composer.json`.
 
 You don't need to have PHP or anything at all on your system to run it.