v0.4.0

What's Changed

• chore: point the flake at v0.3.0 by @atyrode in #19
• docs: usage section (the one-word manual) + feature list by @atyrode in #20
• feat: spawn omp panes through herdr's agent API by @atyrode in #22
• feat: code herdr-usage — the herdr usage-section publisher by @atyrode in #24

Full Changelog: v0.3.0...v0.4.0