Add a registry user account
npm adduserCreate or verify a user named <username> in the npm registry, and
save the credentials to the .npmrc file.
The username, password, and email are read in from prompts.
You may use this command to change your email address, but not username or password.
To reset your password, go to http://admin.npmjs.org/
You may use this command multiple times with the same user account to authorize on a new machine.
Default: http://registry.npmjs.org/
The base URL of the npm package registry.