feat: am tip cheat sheet + readable man pages + REPL completion refresh

src/cli.rs

@@ -362,6 +362,13 @@ pub enum Command {
     },
     /// Display version and build information
     Version,
+    /// Cheat sheet: the most useful commands, their key options, your
+    /// most-used commands and a rotating tip of the day
+    Tip {
+        /// Show a single random tip instead of the whole page
+        #[arg(long)]
+        random: bool,
+    },
     /// Manage the configuration file
     #[command(subcommand)]
     Config(ConfigCmd),