add: man page and installation make step

cmd/root.go

@@ -19,7 +19,7 @@ var (
 		Use:   "gitw",
 		Short: "Git issue and milestone integration for taskwarrior",
 		Long: `Gitwarrior is a CLI tool to extend the taskwarrior tasks to synch issues and milestones.
-Gitwarrior requires requires the following uda's to be defined: last_gitw_update(date), git_number(number), git_type(string), git_comment_ids(string).`,
+Gitwarrior requires the following uda's to be defined: last_gitw_update(date), git_number(number), git_type(string), git_comment_ids(string).`,
 	}
 )