fix: unify coder create and coder delete help message (#15752)

Closes #15668

cli/testdata/coder_create_--help.golden

@@ -1,7 +1,7 @@
 coder v0.0.0-devel
 
 USAGE:
-  coder create [flags] [name]
+  coder create [flags] [workspace]
 
   Create a workspace
 

cli/testdata/coder_delete_--help.golden

@@ -7,6 +7,10 @@ USAGE:
 
   Aliases: rm
 
+    - Delete a workspace for another user (if you have permission):
+  
+       $ coder delete <username>/<workspace_name>
+
 OPTIONS:
       --orphan bool
           Delete a workspace without deleting its resources. This can delete a