Issue #3101209 by Sutharsan, longwave, smustgrave: Document the correct web-root default value

(cherry picked from commit 086528af1fc44a044e80098cbba58ce9346c4dac)

Author: alexpott

README.md

@@ -103,7 +103,8 @@ This makes it possible to configure a project with different file layouts; for
 example, either the `drupal/drupal` file layout or the
 `drupal-composer/drupal-project` file layout could be used to set up a project.
 
-If a web-root is not explicitly defined, then it will default to `./`.
+If a web-root is not explicitly defined, then it will default to `.`, the same
+directory as the composer.json file.
 
 ### Altering Scaffold Files