add bash-it-docker to readme

![container](http://i.giphy.com/VNC7FTY49C0zC.gif)

README.md

@@ -36,6 +36,17 @@ fi
 
 Refer to the official [Bash documention](https://www.gnu.org/software/bash/manual/bashref.html#Bash-Startup-Files) to get more info.
 
+
+## Install Docker (NEW)
+
+You can try Bash-it in an isolated enviroment without changing any local files via Docker Container.  
+(Bash Shell v.4.4 with bash-it, bats and bash-completion based on Alpine Linux).   
+
+`docker pull ellerbrock/bash-it`
+
+Have a look in our [bash-it-docker](https://github.com/Bash-it/bash-it-docker) Repository for further informations.
+
+
 ## Update
 
 To update Bash-it, simply run: