Appearance and chapters update

In this release, the following points have been updated:

• Updated outline appearance (second level was not good)
• Updated heading appearance (I was a bit too generous with spacing)
• Added Specifications and Summary chapters
• Added bibliography example
• Corrected some other appearance issue and things (I don't remember all, I should commit more often)

Thanks for reading and if you encounter any issue, feel free to open an issue or suggest a PR.