Enhance documentation with dynamic config example (#4119)

* Enhance documentation with dynamic config example

Added note on dynamic configuration syntax for overridden options.

* Add comments

Author: alexkart

docs/basics.md

@@ -239,6 +239,35 @@ task my_task
 
 Since `current_date` is overridden, the callback is never executed.
 
+:::note
+If you need to create a new configuration option based on the overridden one, use dynamic configuration syntax:
+
+```php
+
+set('dir_name', 'test');
+
+// calling get during recipe initialization will give you the original value defined above
+set('uses_original_dir_name', '/path/to/' . get('dir_name'));
+
+// use dynamic configuration syntax if you need to get a value passed via -o option
+set('uses_overridden_dir_name', function () {
+    return '/path/to/' . get('dir_name');
+});
+
+task('my_task', function () {
+    writeln('Path: {{uses_original_dir_name}}');
+    writeln('Path: {{uses_overridden_dir_name}}');
+});
+```
+
+```sh
+$ dep my_task deployer.org -v -o dir_name="prod"
+task my_task
+[deployer.org] Path: /path/to/test
+[deployer.org] Path: /path/to/prod
+```
+:::
+
 ---
 
 By now, you should have a solid understanding of Deployer’s basics, from defining tasks and hosts to working with