Minor fixes: Typos, Formatting, Notations

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.2+
| Fixed tickets | -

Beside fixing some typos and formatting, this PR updates notations of *doctrine* to *Doctrine* and makes the notations of database relationships consistent. For the latter, I hope you agree with changing all the different notations like "oneToMany", "One-To-Many", "one-to-many", `one-to-many` etc. to what's promoted most by Google and Wikipedia: all lowercase with hyphens and no literal formatting.