Add the reason why we have IsSerial

The following adds a reason for the introduction of IsSerial. The basic
idea is that we want to provide a more holistic approach to handling the
formatting directives in the CLI without having to resorting to magic
string checking.

cmd/juju/cloud/list.go

@@ -175,10 +175,14 @@ func (c *listCloudsCommand) getCloudList(ctxt *cmd.Context) (*cloudList, error)
 }
 
 func (c *listCloudsCommand) Run(ctxt *cmd.Context) error {
-	// TODO: (stickupkid) IsSerial states that its machine is serialisable, we
-	// shouldn't prompt in those situations. In an ideal world we would move
-	// this into MaybePrompt, but the changes may have unintended consequences
-	// without proper understanding.
+	// TODO (stickupkid): IsSerial states that its machine is serialisable, we
+	// shouldn't prompt in those situations. This is a general clean up of how
+	// we handle formatting directives the user has requested.
+	// The aim is to provide a more holistic approach at the CLI, rather than
+	// magic string checking.
+	// In an ideal world we would move this into MaybePrompt, but the changes
+	// may have unintended consequences without proper understanding.
+	// See: https://discourse.jujucharms.com/t/cli-serialisable-output-formats/2490
 	// Should fix this for Juju 3.0
 	c.ReadOnly = ctxt.IsSerial()
 	if err := c.MaybePrompt(ctxt, "list clouds from"); err != nil {