docs: explicitly defining the optional nature of the ManyToOne and On…

…eToMany relationship when viewed from the child entity (typeorm#4722)

* Update many-to-one-one-to-many-relations.md

Explicitly defining the optional nature of the ManyToOne and OneToMany relationship when viewed from the child entity.

* Update docs/many-to-one-one-to-many-relations.md

Punctuation and more accurate semantics.

Co-Authored-By: Toby Hinloopen <toby@bonaroo.nl>

docs/many-to-one-one-to-many-relations.md

@@ -45,7 +45,7 @@ export class User {
 Here we added `@OneToMany` to the `photos` property and specified the target relation type to be `Photo`.
 You can omit `@JoinColumn` in a `@ManyToOne` / `@OneToMany` relation.
 `@OneToMany` cannot exist without `@ManyToOne`.
-If you want to use `@OneToMany`, `@ManyToOne` is required.
+If you want to use `@OneToMany`, `@ManyToOne` is required. However, the inverse is not required: If you only care about the `@ManyToOne` relationship, you can define it without having `@OneToMany` on the related entity.
 Where you set `@ManyToOne` - its related entity will have "relation id" and foreign key.
 
 This example will produce following tables: