fix: indentation error when registering

src/mastodon.rs

@@ -101,9 +101,9 @@ pub fn register(host: &str, screen_name: &str) {
 
     println!(
         "Please insert the following block at the end of your configuration file:
-        [mastodon.{}]
-        twitter_screen_name = \"{}\"
-        {}",
+[mastodon.{}]
+twitter_screen_name = \"{}\"
+{}",
         screen_name.to_lowercase(),
         screen_name,
         toml