spaces after section headings in module docstrings

Stream: mathlib4

[Kevin Buzzard]

Mathlib currently has

/-!
# Number field discriminant
This file defines the discriminant of a number field.

## Main result

* `NumberField.abs_discr_gt_two`: **Hermite-Minkowski Theorem**. A nontrivial number field has
discriminant greater than `2`.

* `NumberField.finite_of_discr_bdd`: **Hermite Theorem**. Let `N` be an integer. There are only
finitely many number fields (in some fixed extension of `ℚ`) of discriminant bounded by `N`.

## Tags
number field, discriminant
-/

So what is the rule about whether there's a space after ## Heading? Or is the rule that there is no rule?

[Yaël Dillies]

I think the space should be there, for readability