Added three new MySQL learning resources

[connectwithvanshika]

This commit adds the following MySQL tutorials to the free-programming-books list:

1. Introduction to MySQL - MySQL Tutorial (HTML)
2. SQLBolt - Interactive MySQL Lessons (Interactive)
3. Mode SQL Tutorial - Mode Analytics (Interactive)

These resources provide comprehensive and interactive learning materials for beginners and intermediate learners to understand MySQL concepts.

[github-actions]

Linter failed, fix the error(s):

free-programming-books/books/free-programming-books-langs.md
1666:1-1672:74  warning  Alphabetical ordering: swap l.1670 and l.1669          alphabetize-lists      remark-lint
1666:1-1672:74  warning  Alphabetical ordering: swap l.1672 and l.1671          alphabetize-lists      remark-lint
1670:3-1670:58  warning  Remove trailing slash (https://www.mysqltutorial.org)  no-url-trailing-slash  remark-lint
1671:3-1671:62  warning  Remove trailing slash (https://sqlbolt.com)            no-url-trailing-slash  remark-lint