Merge pull request #1009 from aanand/update-docker-install-instructions

Point at official Docker install instructions rather than repeating them

docs/install.md

@@ -10,20 +10,11 @@ Compose with a `curl` command.
 
 ### Install Docker
 
-First, you'll need to install Docker version 1.3 or greater.
+First, install Docker version 1.3 or greater:
 
-If you're on OS X, you can use the
-[OS X installer](https://docs.docker.com/installation/mac/) to install both
-Docker and the OSX helper app, boot2docker. Once boot2docker is running, set the
-environment variables that'll configure Docker and Compose to talk to it:
-
-    $(boot2docker shellinit)
-
-To persist the environment variables across shell sessions, add the above line
-to your `~/.bashrc` file.
-
-For complete instructions, or if you are on another platform, consult Docker's
-[installation instructions](https://docs.docker.com/installation/).
+- [Instructions for Mac OS X](http://docs.docker.com/installation/mac/)
+- [Instructions for Ubuntu](http://docs.docker.com/installation/ubuntulinux/)
+- [Instructions for other systems](http://docs.docker.com/installation/)
 
 ### Install Compose