Remove --save option as it isn't required anymore

Author: stevemoser

README.md

@@ -38,10 +38,10 @@ For the latest stable version, run:
 
 ```sh
 # TypeScript 2.3.3 or later
-npm install --save tslib
+npm install tslib
 
 # TypeScript 2.3.2 or earlier
-npm install --save tslib@1.6.1
+npm install tslib@1.6.1
 ```
 
 ## bower