Auto merge of #373 - Turbo87:patch-1, r=Amanieu
Auto merge of #373 - Turbo87:patch-1, r=Amanieu

changelog: Fix heading levels

The "Added, Fixed and Changed" headings should be one level below the individual versions to nest them properly. This gives dependency update services (renovatebot, dependatbot, etc.) a chance to parse the changelog and extract the changes for their PRs :)

rust-lang/hashbrown,rust-lang/hashbrown