docs: update readme cache instructions

Correcting typo

Author: estrellajm

README.md

@@ -128,7 +128,7 @@ Global package:
 ```bash
 npm uninstall -g @angular/cli
 npm cache verify
-# if npm version is < 5 the use `npm cache clean`
+# if npm version is < 5 then use `npm cache clean`
 npm install -g @angular/cli@latest
 ```