Add changelog contents to release notes

[guhcampos]

Feature Description

This may sound like a pet peeve, but for someone closely following the development of this provider for work it would be immensely helpful to have the changes from CHANGELOG.md added to the github releases. This way the e-mail notifications we get when there's a new release would contain all documented changes, which aids in the decision of upgrading or not our Terraform modules with the new version.

Describe Alternatives

I'm not sure what's the release model of this project, but to the user the relevant outcome is to have the changes published in release metadata.

Additional context

As of today, all release notes contain unhelpful text such as:

chore(changelog): update CHANGELOG for v2.45.1

see https://github.com/newrelic/terraform-provider-newrelic/releases

So to find out what changed, one has to open github, navigate to the releases page, click the commit id of said release and navigate to the CHANGELOG.md file of that specific commit. I know it does not sound like the end of the world, but most of us have to keep track of dozens of package releases a day so this can get a bit of in the way.