docs: correct spelling of example cli usage (#161)

Author: nmcdnld

README.md

@@ -73,7 +73,7 @@ Run `nx affected:test` to execute the unit tests affected by a change.
 
 ## Running end-to-end tests
 
-Run `ng e2e my-app` to execute the end-to-end tests via [Cypress](https://www.cypress.io).
+Run `nx e2e my-app` to execute the end-to-end tests via [Cypress](https://www.cypress.io).
 
 Run `nx affected:e2e` to execute the end-to-end tests affected by a change.