Allow grouping of footers per changelog

[maulik13]

Hey guys, I am back with more requests :)

I am trying to have some of our team members get onboard using semantic-release using go-semantic-release. And they have one use case for a changelog where they would like footers to be grouped in to a separate section.

Example,
The team will write configuration changes in a separate footer for multiple commits.

feat: ...

Config-Change: foo.bar is added to handle the drink count. 

When a release is created they would then like to gather all "Config-Change" entries in to a dedicated section like so:

---

# CHANGELOG.md

Config Changes

• foo.bar is added to handle the drink count
• foo.super block is added to handle superpowers

  {
    "foo": {
       "super": {
           "activate": false,
           "boo": 3
      }
    }
  }
  

If you guys want, I can look in to this.

[Nightapes]

When you want you can have a look and open an PR. Is a cool feature