docs: Fix minor typos in Contributing (#299)

CONTRIBUTING.md

@@ -6,12 +6,12 @@ All you need is the [sentry-dart](https://github.com/getsentry/sentry-dart/tree/
 
 All you need is the [sentry-flutter](https://github.com/getsentry/sentry-dart/tree/main/flutter) and `sentry-dart` as stated above.
 
-The SDK currently supports Android, iOS and Web. We build the example app for these targets in 3 platforms: Windows, macOS and Linux.
+The SDK currently supports Android, iOS, and Web. We build the example app for these targets on 3 platforms: Windows, macOS, and Linux.
 This is to make sure you'd be able to contribute to this project if you're using any of these operating systems.
 
-We also run CI against the Flutter `stable` and `beta` channels so you should be able to build it if you're in one of those.
+We also run CI against the Flutter `stable` and `beta` channels, so you should be able to build it if you're in one of those.
 
-The Flutter SDK has our Native SDKs embedded, if you wish to learn more about them, they sit at:
+The Flutter SDK has our Native SDKs embedded if you wish to learn more about them, they sit at:
 
 [sentry-java](https://github.com/getsentry/sentry-java) for the Android integration.
 [sentry-cocoa](https://github.com/getsentry/sentry-cocoa) for the Apple integration.
@@ -22,7 +22,7 @@ The Flutter SDK has our Native SDKs embedded, if you wish to learn more about th
 * The Dart SDK (if you want to change `sentry-dart`)
 * The Flutter SDK (if you want to change `sentry-dart` or `sentry-flutter`)
 * Android: Android SDK (`sentry-java`) with NDK (`sentry-native`): The example project includes C++.
-* iOS: Cocoa SDK (`sentry-cocoa`), you'll need a Mac with xcode installed.
+* iOS: Cocoa SDK (`sentry-cocoa`), you'll need a Mac with Xcode installed.
 * Web: No additional dependencies.
 
 ### Static Code Analysis, Tests, Formatting, Pub Score and Dry publish