Review the documentation for developers

[windkit]

The performance difference between default build options and the one we have now is unnoticeable

As we tested before https://github.com/leo-project/notes/tree/53926f8d26b4a0ada9d9917e38af0a1fd5ac3144/leofs/benchmark/leofs/1.4/1.4.0/erlang_options/20151119_1m_r95w5_30min_1

It is also easier to download a erlang package from erlang solution instead of building erlang from source

I have also tried to create a dev dockerfile with PR https://github.com/leo-project/leofs/pull/849