docs: update SSH command format to use suffix (#18085)

Refactor the workspace SSH command syntax across the project to use the
"workspace.coder" format instead of "coder.workspace". This standardizes
the SSH host entries for better consistency and clarity.

This is a follow-up from #17445 and recommends using the suffix-based
format for all new Coder versions.

<img width="418" alt="image"
src="https://github.com/user-attachments/assets/3893f840-9ce1-4803-a013-736068feb328"
/>

cli/testdata/coder_--help.golden

@@ -18,7 +18,7 @@ SUBCOMMANDS:
     completion        Install or update shell completion scripts for the
                       detected or chosen shell.
     config-ssh        Add an SSH Host entry for your workspaces "ssh
-                      coder.workspace"
+                      workspace.coder"
     create            Create a workspace
     delete            Delete a workspace
     dotfiles          Personalize your workspace by applying a canonical

cli/testdata/coder_config-ssh_--help.golden

@@ -3,7 +3,7 @@ coder v0.0.0-devel
 USAGE:
   coder config-ssh [flags]
 
-  Add an SSH Host entry for your workspaces "ssh coder.workspace"
+  Add an SSH Host entry for your workspaces "ssh workspace.coder"
 
     - You can use -o (or --ssh-option) so set SSH options to be used for all
   your