Fix typos in REST Example.

Here is the patch.

Found a couple more.

Improve the code

#6 expands the scope beyond spelling errors and typos in the REST example to include code style changes across several example modules.

The changes themselves look fine to me.

#4 covers the scope of the ticket.

+++ b/modules/theming_example/src/Controller/ThemingPageController.php
@@ -1,14 +1,13 @@
+ *

+++ b/modules/theming_example/templates/theming-example-text-form.html.twig
@@ -1,3 +1,9 @@
+ * @file

NW for empty ones, but I will fix them on committing.

Thanks!

Will commit #4 and leave #6 with NW to a new issue.

Needs followup for #6

Automatically closed - issue fixed for 2 weeks with no activity.