message: Update README.md
  Summary:
  Rename from "OS X" to "macOS"
  Closes
diff: @@ -13,7 +13,7 @@ source.
  We use package managers to resolve third-party library dependencies.
  -### Mac OS X
  +### macOS
  You will need Xcode with command line tools installed. To get the command line tools, use:
  ```
  @@ -194,7 +194,7 @@ PATH=/path/to/android/sdk/build-tools/xx.y.zz:$PATH redex [... arguments ...]
  After you run redex, you'll need to re-sign your app. You can re-sign manually
  using these instructions:
  -http://developer.android.com/tools/publishing/app-signing.html#signing-manually.
  +https://developer.android.com/tools/publishing/app-signing.html#signing-manually.
  You can also tell redex to sign for you. If you want to sign with the debug
  key, you can simply do:
  