Make hugo.toml the new config.toml

Both will of course work, but hugo.toml will win if both are set.

We should have done this a long time ago, of course, but the reason I'm picking this up now is that my VS Code setup by default picks up some
JSON config schema from some random other software which also names its config files config.toml.

Fixes #8979

commands/commands.go

@@ -177,7 +177,7 @@ Complete documentation is available at https://gohugo.io/.`,
 		},
 	})
 
-	cc.cmd.PersistentFlags().StringVar(&cc.cfgFile, "config", "", "config file (default is path/config.yaml|json|toml)")
+	cc.cmd.PersistentFlags().StringVar(&cc.cfgFile, "config", "", "config file (default is hugo.yaml|json|toml)")
 	cc.cmd.PersistentFlags().StringVar(&cc.cfgDir, "configDir", "config", "config dir")
 	cc.cmd.PersistentFlags().BoolVar(&cc.quiet, "quiet", false, "build in quiet mode")
 

commands/new_site.go

@@ -83,6 +83,7 @@ func (n *newSiteCmd) doNewSite(fs *hugofs.Fs, basepath string, force bool) error
 			return errors.New(basepath + " already exists and is not empty. See --force.")
 
 		case !isEmpty && force:
+			// TODO(bep) eventually rename this to hugo.
 			all := append(dirs, filepath.Join(basepath, "config."+n.configFormat))
 			for _, path := range all {
 				if exists, _ := helpers.Exists(path, fs.Source); exists {