Update installation instructions

README.md

@@ -29,11 +29,11 @@ The preferred method is to install Electron as a development dependency in your
 app:
 
 ```sh
-npm install electron --save-dev --save-exact
+npm install electron --save-dev [--save-exact]
 ```
 
-The `--save-exact` flag is recommended as Electron does not follow semantic
-versioning. For info on how to manage Electron versions in your apps, see
+The `--save-exact` flag is recommended for Electron prior to version 2, as it does not follow semantic
+versioning. As of version 2.0.0, Electron follows semver, so you don't need `--save-exact` flag. For info on how to manage Electron versions in your apps, see
 [Electron versioning](docs/tutorial/electron-versioning.md).
 
 For more installation options and troubleshooting tips, see