Add some information about what an address can be for CLI commands (#9233)

cli/src/lib.rs

@@ -1,3 +1,23 @@
+macro_rules! ACCOUNT_STRING {
+    () => {
+        r#"Can be:
+  * a bs58 pubkey string
+  * path to keypair file
+  * '-' to take json-encoded keypair string from stdin
+  * 'ASK' to ask for a passphrase
+  * path to hardware wallet (usb://..)"#
+    };
+}
+
+#[macro_use]
+macro_rules! pubkey {
+    ($arg:expr, $help:expr) => {
+        $arg.takes_value(true)
+            .validator(is_valid_pubkey)
+            .help(concat!($help, ACCOUNT_STRING!()))
+    };
+}
+
 pub mod cli;
 pub mod cluster_query;
 pub mod display;