Update CONTRIBUTING.md
Remove some redundant words.
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index ea119ce..1c495ae 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -12,15 +12,15 @@
* An ssh client (used to authenticate with GitHub).
* Python (used by some of our tools).
* The Dart SDK (see [Issue #54](https://github.com/flutter/flutter/issues/54)
- about downloading the Dart SDK automatically). Note: If you're also
+ about downloading the Dart SDK automatically). _If you're also
working on the Flutter engine, you can use the copy of the Dart SDK
- in `.../engine/src/third_party/dart-sdk/dart-sdk`.
+ in `.../engine/src/third_party/dart-sdk/dart-sdk`._
- [https://www.dartlang.org/downloads/archive/](https://www.dartlang.org/downloads/archive/)
* The Android platform tools (see [Issue #55](https://github.com/flutter/flutter/issues/55)
about downloading the Android platform tools automatically).
- Note: If you're also working on the Flutter engine, you can use the
+ _If you're also working on the Flutter engine, you can use the
copy of the Android platform tools in
- `.../engine/src/third_party/android_tools/sdk/platform-tools`.
+ `.../engine/src/third_party/android_tools/sdk/platform-tools`._
- Mac: `brew install android-platform-tools`
- Linux: `sudo apt-get install android-tools-adb`
