mdbooks v3.8.1

[sasha-astiadi]

publish these books by the end of v3.8.0 sprint

• [ ] https://github.com/threefoldfoundation/books/issues/4
• [ ] https://github.com/threefoldfoundation/books/issues/5
• [ ] https://github.com/threefoldfoundation/books/issues/7
• [ ] https://github.com/threefoldfoundation/books/issues/6
• [x] https://github.com/threefoldfoundation/books/issues/8
• [ ] https://github.com/threefoldfoundation/books/issues/2

[sasha-astiadi]

everything is moved to archived , @despiegk wHy? I will remove this issue from project 3.8