Steps mentioned here: jekyll/jekyll#3984
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
brew install ruby
sudo gem install jekyll
Added _config_dev.yml to override properties in _config.yml. We can run jekyll like this
jekyll serve --config _config.yml,_config_dev.yml
In Dev environment we can specify some config which will override the default config.