Create issue-209

[ph818]

Add changelog for Add MemoryHigh to example systemd unit file

What is the purpose of this change? What does it change?

Was the change discussed in an issue or in the forum before?

Closes #209

Checklist

• [x] I have enabled maintainer edits for this PR
• [ ] I have added tests for all changes in this PR
• [ ] I have added documentation for the changes (in the manual)
• [x] There's a new file in changelog/unreleased/ that describes the changes for our users (template here)
• [ ] I have run gofmt on the code in all commits
• [ ] All commit messages are formatted in the same style as the other commits in the repo
• [x] I'm done, this Pull Request is ready for review

[MichaelEischer]

I don't think we need a changelog entry for PR #210, it just adds a new comment. (Besides that, the file should have been added directly to that PR)