Common subcommand naming scheme (#208)

drop tea mile alias

document command schema in CONTRIBUTING.md

and update this file, its a plain copy from gitea

add "list" as alias for "ls" subcommand

add singular command aliases

Co-authored-by: Norwin Roosen <git@nroo.de>
Reviewed-on: https://gitea.com/gitea/tea/pulls/208
Reviewed-by: 6543 <6543@noreply.gitea.io>
Reviewed-by: techknowlogick <techknowlogick@gitea.io>

cmd/milestones/list.go

@@ -19,6 +19,7 @@ import (
 // CmdMilestonesList represents a sub command of milestones to list milestones
 var CmdMilestonesList = cli.Command{
 	Name:        "ls",
+	Aliases:     []string{"list"},
 	Usage:       "List milestones of the repository",
 	Description: `List milestones of the repository`,
 	Action:      RunMilestonesList,