v0.19.0

What's Changed

• test: a line budget for the docs, so terser stays terser by @scharissis in #297 (closes #282)
• docs: cut the README from 445 to 312 lines by @scharissis in #298 (closes #283)
• docs: reference.md argues where it should state — tighten the flag table and the verb sections by @scharissis in #300 (closes #284)
• docs: give behaviour.md sections, cover plan and health by @scharissis in #301 (closes #285)
• docs: cover plan and health in security.md by @scharissis in #302 (closes #286)
• docs: run-data.md is 702 lines — keep the sample reports, cut the argument by @scharissis in #303 (closes #287)
• docs: the same plain-English pass over install.md, hardening.md and releasing.md by @scharissis in #304 (closes #288)
• docs: add GitHub About text block, fix drifted tagline copies by @scharissis in #305 (closes #289)

Full Changelog: v0.18.0...v0.19.0