"Features" and other release subsections have the save header level as the release.

version: 3.1.24

The subsections of a release have the same header level, it's confusing.

Result:
```
# Changelog

...

### 0.0.2 (2021-05-11)


### Features

* **test-feature:** add feature X (...)

```

Expected result:
```
# Changelog

...

### 0.0.2 (2021-05-11)


##### Features

* **test-feature:** add feature X (...)

```