Update the command to run the CLI in the README file

[joaopalmeiro]

Hi! 👋

After going through the README file, in the From the command line subsection, I think that npx npm-package-json-lint should be replaced by npx npm-package-json-lint ., in order to be in line with the documentation.

It may also be interesting to add the link for a base configuration, such as the one available in this page or in this section (in the README subsection mentioned above or in the following one).