update markdown link

[you should know that]

in the Russian version on the Mythbusters.md page, the link to the book file should be updated in the section "Изучайте С++ только по стандарту"

now the link leads to https://github.com/salmer/CppDeveloperRoadmap/blob/main/Russian/Books.md
but should lead to https://github.com/salmer/CppDeveloperRoadmap/blob/main/Russian/Books/Overview.md