update readme for installation
update readme for installation

jupyter/jupyter-js-plugins,blink1073/jupyter-js-plugins,jupyter/jupyter-js-plugins,blink1073/jupyter-js-plugins,jupyter/jupyter-js-plugins,blink1073/jupyter-js-plugins,jupyter/jupyter-js-plugins,jupyter/jupyter-js-plugins,blink1073/jupyter-js-plugins,blink1073/jupyter-js-plugins