Add dialog_ok if the user declines the update (#609)

* Add dialog_ok if the user declines the update

* Remove linebreak which doesn't actually appear on console (?)

* rustfmt

src/common/release.rs

@@ -208,6 +208,12 @@ pub fn perform_version_check() {
                 }
             } else {
                 info!("User declined the update.");
+                dialog::dialog_ok(
+                    "This update has been declined.\n\n\
+                    If you'd like to disable update checking in the future,\
+                    please adjust the 'Auto-Update' setting in the Modpack menu."
+                        .to_string(),
+                );
             }
         }
         Err(e) => {