update description

Author: bahmutov

README.md

@@ -1,5 +1,5 @@
 # netlify-plugin-cypress [![CircleCI](https://circleci.com/gh/cypress-io/netlify-plugin-cypress/tree/master.svg?style=svg&circle-token=9cbb587a5a0ae4ce28b011dd03d10d66de906708)](https://circleci.com/gh/cypress-io/netlify-plugin-cypress/tree/master)
-> Runs Cypress end-to-end tests after Netlify builds the site
+> Runs Cypress end-to-end tests after Netlify builds the site but before it is deployed
 
 **Note:** currently the built site is served statically and tested _without proxying redirects_.