Update README-RU.md - Update to the Russian README to be closer to th…

[Nickkkwith3ks]

…e main english README.md

Updated some parts of the Russian README file to be closer to the main one in style and formatting. Still many links that are on the English main readme are missing and or in the wrong places.

Checklist:

• [x] I have read freeCodeCamp's contribution guidelines.
• [x] My pull request has a descriptive title (not a vague title like Update index.md)
• [x] My pull request targets the main branch of freeCodeCamp.

Closes #XXXXX