message: Added argument to build.sh
  The script `build.sh` requires an argument. On linux, the argument is `ubuntu` and on macOS it is `darwin`.
diff: @@ -116,7 +116,7 @@ git clone https://github.com/eosio/eos --recursive
  cd eos
  git checkout DAWN-2018-02-14
  git submodule update --recursive
  -./build.sh
  +./build.sh ubuntu
  ```
  For ease of contract development, one further step is required:
  @@ -162,7 +162,7 @@ git clone https://github.com/eosio/eos --recursive
  cd eos
  git checkout DAWN-2018-02-14
  git submodule update --recursive
  -./build.sh
  +./build.sh darwin
  ```
  For ease of contract development, one further step is required:
  