minor fixes

Author: iliakan

1-js/05-data-types/11-date/6-get-seconds-today/solution.md

@@ -23,4 +23,6 @@ function getSecondsToday() {
   let d = new Date();
   return d.getHours() * 3600 + d.getMinutes() * 60 + d.getSeconds();
 }
+
+alert( getSecondsToday() );
 ```

1-js/13-modules/01-modules-intro/article.md

@@ -57,6 +57,10 @@ Like this:
 
 The browser automatically fetches and evaluates the imported module (and its imports if needed), and then runs the script.
 
+```warn header="Modules work only via HTTP, not in local files"
+If you try to open a web-page locally, via `file://` protocol, you'll find that `import/export` directives don't work. Use a local web-server, such as [static-server](https://www.npmjs.com/package/static-server#getting-started) or VS Code [Live Server Extension](https://marketplace.visualstudio.com/items?itemName=ritwickdey.LiveServer) to test them.
+```
+
 ## Core module features
 
 What's different in modules, compared to "regular" scripts?