refactor: more seamless SSH connections

cli/server/add.go

@@ -316,14 +316,10 @@ to start running Abra commands against it.
 
 This command can also provision your server ("--provision/-p") so that it is
 capable of hosting Co-op Cloud apps. Abra will default to expecting that you
-have a working SSH config for the host in your ~/.ssh/config file. E.g. for
-"example.com", you'll want to have something like:
-
-Host example.com
-  Hostname 192.168.178.31  # domain name also works
-  User myuserontheserver
-  Port 12345
-  IdentityFile ~/.ssh/mysecretkey.local
+have a running ssh-agent and are using SSH keys to connect to your new server.
+Abra will also read your SSH config (matching "Host" as <domain>). SSH
+connection details precedence follows as such: command-line > SSH config >
+guessed defaults.
 
 If you have no SSH key configured for this host and are instead using password
 authentication, you may pass "--ssh-auth password" to have Abra ask you for the
@@ -345,7 +341,7 @@ Example:
 
     abra server add --provision --traefik varia.zone glodemodem 12345
 
-Abra will construct the following SSH connection string then:
+Abra will construct the following SSH connection and Docker context:
 
     ssh://globemodem@varia.zone:12345