Added documentation for setting up existing projects

README.md

@@ -82,7 +82,7 @@ The `mymagento.test` above defines the hostname to use, and the `2.2.6` defines
 
 After the one-liner above completes running, you should be able to access your site at `http://mymagento.test`.
 
-### Manual Quick Setup
+### Manual Quick Setup (New Project)
 
 Same result as the one-liner above. Just replace `mymagento` references with the hostname that you wish to setup.
 
@@ -104,6 +104,23 @@ bin/setup mymagento.test
 open http://mymagento.test
 ```
 
+### Manual Quick Setup (Existing Project)
+
+Just replace `mymagento.test` references with the hostname that you wish to use.
+
+```
+# Quick setup for an existing instance of Magento 2
+curl -s https://raw.githubusercontent.com/markoshust/docker-magento/master/lib/template|bash -s - magento-2
+
+# Replace the contents of /src with the source code of your existing Magento instance
+
+echo "127.0.0.1 mymagento.test" | sudo tee -a /etc/hosts
+
+bin/start
+
+open http://mymagento.test
+```
+
 ## Setup a New Magento 2 Project
 
 1. Create the project template by going to the place you want the new project (ex. cd ~/Sites/magento2), then run