Add sentence to tell other options are ignored when running check-theme

Author: GuillaumeGomez

src/librustdoc/config.rs

@@ -281,12 +281,12 @@ impl Options {
         // check for deprecated options
         check_deprecated_options(&matches, &diag);
 
-        let to_check = matches.opt_strs("theme-checker");
+        let to_check = matches.opt_strs("check-theme");
         if !to_check.is_empty() {
             let paths = theme::load_css_paths(static_files::themes::LIGHT.as_bytes());
             let mut errors = 0;
 
-            println!("rustdoc: [theme-checker] Starting tests!");
+            println!("rustdoc: [check-theme] Starting tests! (Ignoring all other arguments)");
             for theme_file in to_check.iter() {
                 print!(" - Checking \"{}\"...", theme_file);
                 let (success, differences) = theme::test_theme_against(theme_file, &paths, &diag);
@@ -378,7 +378,7 @@ impl Options {
                                                default theme", theme_s))
                         .warn("the theme may appear incorrect when loaded")
                         .help(&format!("to see what rules are missing, call `rustdoc \
-                                        --theme-checker \"{}\"`", theme_s))
+                                        --check-theme \"{}\"`", theme_s))
                         .emit();
                 }
                 themes.push(theme_file);