touch: move help strings to markdown file

src/uu/touch/src/touch.rs

@@ -19,10 +19,10 @@ use time::macros::{format_description, offset, time};
 use time::Duration;
 use uucore::display::Quotable;
 use uucore::error::{FromIo, UError, UResult, USimpleError};
-use uucore::{format_usage, show};
+use uucore::{format_usage, help_about, help_usage, show};
 
-static ABOUT: &str = "Update the access and modification times of each FILE to the current time.";
-const USAGE: &str = "{} [OPTION]... [USER]";
+const ABOUT: &str = help_about!("touch.md");
+const USAGE: &str = help_usage!("touch.md");
 pub mod options {
     // Both SOURCES and sources are needed as we need to be able to refer to the ArgGroup.
     pub static SOURCES: &str = "sources";

src/uu/touch/touch.md

@@ -0,0 +1,7 @@
+# touch
+
+```
+touch [OPTION]... [USER]
+```
+
+Update the access and modification times of each `FILE` to the current time.