docs: remove --save flag (facebookarchive#2008)

Summary:
--save is no longer needed.
Pull Request resolved: facebookarchive#2008

Differential Revision: D15239571

Pulled By: claudiopro

fbshipit-source-id: 78227dc4d3748ea64d769198a0dd9886f5e30b0c

docs/Overview.md

@@ -17,15 +17,15 @@ Draft.js was introduced at [React.js Conf](https://conf2016.reactjs.org/schedule
 Draft.js is distributed via npm. It depends on React and React DOM which must also be installed.
 
 ```sh
-npm install --save draft-js react react-dom
+npm install draft-js react react-dom
 # or alternately
 yarn add draft-js react react-dom
 ```
 
 Draft.js uses some modern ecmascript features which are not available to IE11 and not part of create-react-app's default babel config. If you're running into problems out-of-the-box try installing a shim or polyfill alongside Draft.
 
 ```sh
-npm install --save draft-js react react-dom babel-polyfill
+npm install draft-js react react-dom babel-polyfill
 # or
 yarn add draft-js react react-dom es6-shim
 ```