setup_env.sh: add requirement notes
setup_env.sh: add requirement notes

shilpi230/lz4-ruby,shilpi230/lz4-ruby,pranjalpatil/lz4-ruby,komiya-atsushi/lz4-ruby,Metaswitch/lz4-ruby,Metaswitch/lz4-ruby,pranjalpatil/lz4-ruby,komiya-atsushi/lz4-ruby,Metaswitch/lz4-ruby,komiya-atsushi/lz4-ruby,Metaswitch/lz4-ruby,shilpi230/lz4-ruby,shilpi230/lz4-ruby,pranjalpatil/lz4-ruby,pranjalpatil/lz4-ruby,komiya-atsushi/lz4-ruby