Install jekyll and troubleshooting

Quick guidence to install jekyll

1. Ruby > 2.5.0
2. install rbenv and ruby-build to install ruby 2.5.0
3. Mac add below script to ~/.bash_profile

   export PATH="$HOME/.rbenv/bin:$PATH"
   eval "$(rbenv init -)"
   

4. gem install jekyll bundle
5. If failed to install ffi

   brew install libtool automake