[install] update main readme also

[skip CI]

Author: jcb91

README.md

@@ -167,9 +167,10 @@ config-editing operations, or only the file-copy operations:
     - `jupyter_notebook_config.json` to enable the serverextension
       `jupyter_nbextensions_configurator`.
 
-Finally, the `--skip-running-check` option flag is provided in order to allow
-the installation to proceed even if a notebook server appears to be currently
-running (by default, the install will not be performed if a notebook server
+Finally, the `--perform-running-check` option flag is provided in order to
+prevent the installation from proceeding if a notebook server appears to be
+currently running
+(by default, the install will still be performed, even if a notebook server
 appears to be running).
 
 An analogous `uninstall` command is also provided, to remove all of the