added clear instructions of how to get the WebDriver running on Raspberry Pi

Fetching-pages-with-WebDriver.md

@@ -15,6 +15,23 @@ The backend can be configured to fetch pages via Chrome using the built in [WebD
         restart: unless-stopped
 ```
 
+If using docker (instead of docker-compose) the following will get ChangeDetection.io and the chromium WebDriver up and running:
+```
+docker run -d \
+  --name changedetection.io \
+  --restart always \
+  -p 5555:5000 \
+  -e WEBDRIVER_URL="http://localhost:4444/wd/hub" \
+  -v datastore-volume:/datastore \
+  dgtlmoon/changedetection.io
+
+docker run -d \
+  --name selenium \
+  -p 4444:4444 \
+  --shm-size="2g" \
+  seleniarm/standalone-chromium
+```
+
 Then visit `/settings` and `[Fetching]` tab and enable the WebDriver/Chrome option
 
 The URL for the WebDriver interface is set with the `WEBDRIVER_URL` environment variable (`http://browser-chrome:4444/wd/hub` by default)