Add Yury Yukhananov to Rookie List

[Retamogordo]

Description

Welcome! We are excited to have you on board. This is your first formal step in making it official that you are a part of the Polkadot Heroes program as either a hero or a rookie. Please fill out your profile details in this pull request. Remember to place your profile in alphabetical order in the list, add your profile image to the ./images subfolder of either the Heroes/ or Rookies/ folder, and fill out all the informational fields in your card. You can copy and paste someone else's card and replace their information with your own.

Make sure to preview your additions in the Heroes/README.md or the Rookies/README.md file to confirm it looks as expected.

Checklist:

• [x] My name is alphabetically ordered by first name in the README
• [x] My profile picture is added to the /images folder of either the Heroes/ or the Rookies/ directory
• [x] All the fields are filled out for my profile (see the other profiles for examples)

[hummusonrails]

Welcome, @Retamogordo! 🎉

Nice to see another PBA Buenos Aires 🇦🇷 alum!