Update README.md

Author: raonigabriel

README.md

@@ -2,6 +2,13 @@
 A custom Docker image containing the theia-ide for Java development
 
 
+## Features
+* Based on https://github.com/theia-ide/theia-apps/tree/master/theia-java-docker
+* The Java used is OpenJDK version instead of IBM one.
+* Java, Maven and Gradle are copied over from another Docker images instead of using the distro version.
+* Project dir is "/home/workspaces" instead of "/home/project"
+* Small footprint: about 1.62 GB instead of 2.2GB
+
 ## Usage
 ```
 $ docker volume create theia_workspaces