correct installer command

README.md

@@ -1,9 +1,10 @@
 # deltachat-ios
 
->  Email-based instant messaging for iOS.
+Email-based instant messaging for iOS.
 
 ![Screenshot Chat List](docs/images/screenshot_chat_list.png) ![Screenshot Chat View](docs/images/screenshot_chat_view.png)
 
+
 ## Testing
 
 Betas are distributed via Testflight. Just scan this QR code with the camera app of your iPhone/iPad
@@ -18,6 +19,7 @@ on your iPhone or iPad to try Deltachat iOS Beta.
 
 Check the Changelog (for TestFlight builds) at the bottom to see what's included.
 
+
 ## How to build with Xcode
 
 You need to install [rustup](https://rustup.rs/) with rust, as well as [cargo-lipo](https://github.com/TimNN/cargo-lipo#installation).
@@ -43,5 +45,5 @@ If Xcode complains about missing header files (different mac versions may or may
 you can force-install them with the following command:
 
 ```bash
-$ installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /
+$ sudo installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /
 ```