(blog) Add challenge 4 of #100DaysOfGatbsy (#20800)
(blog) Add challenge 4 of #100DaysOfGatbsy (#20800)

* Add challenge 4

* chore: format

* Fix capitalization

* Update docs/blog/100days/react-component/index.md

Co-Authored-By: Marcy Sutton <63f38fb7a2c9e72439a06d93cefb66621e8fc496@gatsbyjs.com>

* Add link to accessibility resource

Co-authored-by: GatsbyJS Bot <313a651c59fdaade90d152972001707d94b0975c@gmail.com>
Co-authored-by: Aisha Blake <e0b0dda0a9e0d5d575159802d44d0f5f5c2978c9@gmail.com>
Co-authored-by: Marcy Sutton <63f38fb7a2c9e72439a06d93cefb66621e8fc496@gatsbyjs.com>

ilcm96/ilcm96.github.io