Slight tweak to README file

[brokenmachine]

In the Installation section, the instructions have you add git repo, as well as a require block:

"require": {
"drupal/drush-cmi-tools": "dev-8.x-1.x"
},

I think you only to define the repo, and then when you run the composer require command, composer will add the require statement, so need to add this by hand.