Documentation: rename "where" parameter of checkpoint to "note"

The name "where" may confuse users into thinking that this parameter
actually does something where in fact it's just arbitrary text used to
identify the checkpoint.

Fixes #1373

Documentation/cli/README.md

@@ -93,7 +93,9 @@ Current limitations:
 ## check
 Creates a checkpoint at the current position.
 
-	checkpoint [where]
+	checkpoint [note]
+
+The "note" is arbitrary text that can be used to identify the checkpoint, if it is not specified it defaults to the current filename:line position.
 
 Aliases: checkpoint
 

pkg/terminal/command.go

@@ -356,7 +356,9 @@ If locspec is omitted edit will open the current source file in the editor, othe
 			cmdFn:   checkpoint,
 			helpMsg: `Creates a checkpoint at the current position.
 
-	checkpoint [where]`,
+	checkpoint [note]
+
+The "note" is arbitrary text that can be used to identify the checkpoint, if it is not specified it defaults to the current filename:line position.`,
 		})
 		c.cmds = append(c.cmds, command{
 			aliases: []string{"checkpoints"},
@@ -1954,7 +1956,7 @@ func checkpoints(t *Term, ctx callContext, args string) error {
 	}
 	w := new(tabwriter.Writer)
 	w.Init(os.Stdout, 4, 4, 2, ' ', 0)
-	fmt.Fprintln(w, "ID\tWhen\tWhere")
+	fmt.Fprintln(w, "ID\tWhen\tNote")
 	for _, cp := range cps {
 		fmt.Fprintf(w, "c%d\t%s\t%s\n", cp.ID, cp.When, cp.Where)
 	}