readme: add cask instruction

Author: seanfarley

README.org

@@ -37,6 +37,7 @@ lsp-mode client leveraging microsoft's [[https://github.com/Microsoft/python-lan
              "~/python-language-server/output/bin/Release/osx-x64/publish/Microsoft.Python.LanguageServer"))
    #+END_SRC
 
+For developement, you might find it useful to run =cask install=.
 * Credit
 
 All credit to [[https://cpbotha.net][cpbotha]] on [[https://vxlabs.com/2018/11/19/configuring-emacs-lsp-mode-and-microsofts-visual-studio-code-python-language-server/][vxlabs]]!  This just tidies and packages his