CHANGELOG.md: add v0.0.2 and v0.0.1 changes

[kolyshkin]

Let's prepare for v0.0.2 release. Here's a copy-paste of the changelog:

Changelog

This file documents all notable changes made to this project since it was
split out of runc repository.

The format is based on Keep a Changelog,
and this project adheres to Semantic Versioning.

Unreleased

0.0.2 - 2005-04-25

Added

• CPU burst stats. (introduce cpu burst stat #11)
• CI infrastructure. (Add CI #3, CI: add cgroup v1 (AlmaLinux 8) #6)
• CI: add nolintlint linter. (ci: add nolintlint, fix warnings #10)

Changed

• Mark some fileds with omitempty JSON attribute. (Add omitempty JSON attribute for some fields #9)
• Modernize code by using new Go features. (Modernize code #13)
• CI: switch to golangci-lint v2. (Switch to golangci-lint v2, fix or suppress new warnings #12)

Fixed

• systemd: write rounded CPU quota to cgroupfs. (systemd: Write rounded CPU quota to cgroupfs #4)

0.0.1 - 2025-02-28

Added

• This is an initial release of the code after splitting it from the runc repository,
  according to the proposal.

[AkihiroSuda]

Do we even need to maintain CHANGELOG.md?
GitHub Releases have release notes

[kolyshkin]

Yes, but I'd like the information to be accessible locally. Maybe it's not worth it, I dunno.

[thaJeztah]

Yeah, I was considering the same. While a change-log can be nice, it also easily gets forgotten to be updated, or adds additional maintenance.

For a project that produces binaries (such as runc), I could see it being more relevant (also for potential inclusion in deb, rpm packages), but a bit on the fence for a library module like cgroups

[kolyshkin]

This kind of make sense. We can maintain the changelog under https://github.com/opencontainers/cgroups/releases