add resource for information on managing multiple SSH keys (#210)

README.md

@@ -726,7 +726,7 @@ EC2
 	-	When you start an instance, you need to have at least one [ssh key pair](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-key-pairs.html) set up, to bootstrap, i.e., allow you to ssh in the first time.
 	-	Aside from bootstrapping, you should manage keys yourself on the instances, assigning individual keys to individual users or services as appropriate.
 	-	Avoid reusing the original boot keys except by administrators when creating new instances.
-	-	How to avoid sharing keys; how to add individual ssh keys for individual users.
+	-	Avoid sharing keys and [add individual ssh keys](http://security.stackexchange.com/questions/87480/managing-multiple-ssh-private-keys-for-a-team) for individual users.
 -	**GPU support:** You can rent GPU-enabled instances on EC2. There are [two instance types](http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using_cluster_computing.html). Both sport an NVIDIA card (K520, 1536 CUDA cores and M2050, 448 CUDA cores).
 
 ### EC2 Gotchas and Limitations