Update advanced selectors lesson #29241

- add note to 'MDN article on combinators' link not to do test your skill
  at bottom of linked MDN article for selectors
- add assignment that links to test your skills section of MDN article
  to practice lesson on selectors

intermediate_html_css/intermediate_css_concepts/advanced_selectors.md

@@ -261,7 +261,7 @@ To see what other things you can achieve with attribute selectors, such as searc
 
 1. Complete [CSS Diner](https://flukeout.github.io/). You should be familiar with most of the content in the first couple of exercises, but practice and review never hurt! Don't forget to read the examples and explanations on the right.
 1. Read [Shay Howe's article on Complex Selectors](https://learn.shayhowe.com/advanced-html-css/complex-selectors/). This covers most of the content of this lesson in a bit more detail. As stated in their article, they sometimes use a single colon instead of a double one for pseudo-elements. Please keep in mind that the double colon is now the standard.
-3. Do this [Selectors Assesment](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Styling_basics/Basic_selectors/Selectors_Tasks) from MDN. It'd help you put your newly learned knowledge of selectors to practice!
+1. Do this [Selectors Assesment](https://developer.mozilla.org/en-US/docs/Learn_web_development/Core/Styling_basics/Basic_selectors/Selectors_Tasks) from MDN. It'd help you put your newly learned knowledge of selectors to practice!
 
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