message: update Mac OS readme
diff: @@ -195,14 +195,14 @@ Here is a brief description for compiling Qtum on CentOS, for more details pleas
  ./configure
  make -j4
  -### Build on OSX
  +### Build on Mac OS
  The commands in this guide should be executed in a Terminal application.
  The built-in one is located in `/Applications/Utilities/Terminal.app`.
  #### Preparation
  -Install the OS X command line tools:
  +Install the Mac OS command line tools:
  `xcode-select --install`
  @@ -212,7 +212,7 @@ Then install [Homebrew](https://brew.sh).
  #### Dependencies
  - brew install cmake automake berkeley-db4 libtool boost --c++11 --without-single --without-static miniupnpc openssl pkg-config protobuf qt5 libevent imagemagick --with-librsvg qrencode gmp
  + brew install cmake automake berkeley-db4 libtool boost miniupnpc openssl pkg-config protobuf qt5 libevent imagemagick librsvg qrencode gmp
  NOTE: Building with Qt4 is still supported, however, could result in a broken UI. Building with Qt5 is recommended.
  