Update README.md

README.md

@@ -2,7 +2,15 @@
 
 ### What's this?
 
-Dockerfile that produces an image the contain all nessary prerequisites for working with Android in C++/Qt 
+Virtual environment for making Qt package testing on Android a bit easy.
+Essentially this is a Dockerfile that produces an image that contain all nessary prerequisites for working with Android in C++/Qt. 
+
+The pre-build image for some sdk/ndk combination is located in https://hub.docker.com/r/ttqtc/android_prerequisites_sdk26_ndk21, 
+to use it directly you can do
+```
+  docker run -p 5903:5903 -p 5901:5901 --privileged tqtc/android_prerequisites_sdk26_ndk21
+```
+
 
 For building image simple do
 ```