Don't print "run the command again with --verbose"

Here is a typical error seen by users of Cargo:

```
error[E0601]: `main` function not found in crate `wrong`
  |
  = note: consider adding a `main` function to `src/main.rs`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0601`.
error: could not compile `wrong`

To learn more, run the command again with --verbose.
```

The `--verbose` output is not particularly helpful in this case. The
error is unrelated to what cargo is doing, and passing `--verbose` will
not give useful information about how to proceed. Additionally, it's
unclear that `--verbose` is referring to the cargo command and not
rustc; this is especially true when cargo is wrapped by another build
system (such as Meson, x.py, or Make).

This omits the "run the command again with --verbose" output. --verbose
is still shown in `cargo build --help`, but it's not singled out above
all the other options.

Author: jyn514

src/cargo/lib.rs

@@ -89,13 +89,7 @@ pub fn exit_with_error(err: CliError, shell: &mut Shell) -> ! {
 /// Displays an error, and all its causes, to stderr.
 pub fn display_error(err: &Error, shell: &mut Shell) {
     debug!("display_error; err={:?}", err);
-    let has_verbose = _display_error(err, shell, true);
-    if has_verbose {
-        drop(writeln!(
-            shell.err(),
-            "\nTo learn more, run the command again with --verbose."
-        ));
-    }
+    _display_error(err, shell, true);
     if err
         .chain()
         .any(|e| e.downcast_ref::<InternalError>().is_some())