Removed the redundant cmd to add webpack plugin

Author: code-n-chill

README.md

@@ -43,9 +43,7 @@ else fails, try removing the virtual environment and reinstalling:
 ## Development
 
 1. Run `pipenv shell` to spawn a shell with the virtualenv activated.
-2. Run `lektor plugins add webpack-support` to enable the webpack plugin. This is required
-   only for the very first time.
-3. Run `lektor server -f webpack` to start the Lektor development server. You will be able
+2. Run `lektor server -f webpack` to start the Lektor development server. You will be able
    to see the website at [`http://localhost:5000/`][lektorlocal]. The Lektor
    server will rebuild the site every time you change any content.