clarify the file on which to run `chmod 600`

docs/cloudstack.md

@@ -117,9 +117,9 @@ are not on campus, you can still access your VM via the following methods:
 The second option is generally more convenient. The idea is to SSH into a CSC
 general-use machine first, then SSH from there into your VM.
 
-On any CSC general-use machine, copy your SSH key to the `.ssh` folder in your
-home directory (e.g. via scp). Make sure that it is only readable by you (e.g.
-run `chmod 600` on it). Running `ls -l ~/.ssh` should show something like this:
+On any CSC general-use machine, copy your `id_rsa` file to the `.ssh` folder in your
+home directory (e.g. via scp). Make sure that the `id_rsa` file is only readable by
+you (e.g. run `chmod 600 ~/.ssh/id_rsa`). Running `ls -l ~/.ssh` should show something like this:
 
     total 16
     -rw-r--r-- 1 ctdalek ctdalek  918 Oct 14 12:05 authorized_keys