Add Viceroy version required for --profile-guest

Suggested by @Integralist.

pkg/commands/compute/serve.go

@@ -84,7 +84,7 @@ func NewServeCommand(parent cmd.Registerer, g *global.Data, build *BuildCommand,
 	c.CmdClause.Flag("include-source", "Include source code in built package").Action(c.includeSrc.Set).BoolVar(&c.includeSrc.Value)
 	c.CmdClause.Flag("language", "Language type").Action(c.lang.Set).StringVar(&c.lang.Value)
 	c.CmdClause.Flag("package-name", "Package name").Action(c.packageName.Set).StringVar(&c.packageName.Value)
-	c.CmdClause.Flag("profile-guest", "Profile the Wasm guest under Viceroy. View profiles at https://profiler.firefox.com/.").BoolVar(&c.profileGuest)
+	c.CmdClause.Flag("profile-guest", "Profile the Wasm guest under Viceroy (requires Viceroy 0.9.1 or higher). View profiles at https://profiler.firefox.com/.").BoolVar(&c.profileGuest)
 	c.CmdClause.Flag("profile-guest-dir", "The directory where the per-request profiles are saved to. Defaults to guest-profiles.").Action(c.profileGuestDir.Set).StringVar(&c.profileGuestDir.Value)
 	c.CmdClause.Flag("skip-build", "Skip the build step").BoolVar(&c.skipBuild)
 	c.CmdClause.Flag("timeout", "Timeout, in seconds, for the build compilation step").Action(c.timeout.Set).IntVar(&c.timeout.Value)