Alter E0412 help message wording

The initial wording does not make sense due to an extra 'to'.

There are two potential candidates we can change this to:
 - 'you can import it into scope'
 - 'to import it into scope'

In keeping the changes minimal, we choose the first, as this is more in line with the grammar of the extended candidates help message.

src/librustc_resolve/lib.rs

@@ -3625,7 +3625,7 @@ fn show_candidates(session: &mut DiagnosticBuilder,
             if paths.len() == 1 {
                 session.fileline_help(
                     span,
-                    &format!("you can to import it into scope: `use {};`.",
+                    &format!("you can import it into scope: `use {};`.",
                         &path_strings[0]),
                 );
             } else {