Documentation for 1.0.0: README, guides, screenshots, GitHub files

- README: what Control4Free is and why it reaches menus and sign-in, features,
  a quick start, screenshots, requirements, limitations, credits.
- docs/: installation, playing, troubleshooting (every message the page and the
  app can show), how it works, and the WebSocket protocol.
- CONTRIBUTING.md: building, testing, code style, releasing.
- Screenshots of the page on phones and a PC and of the app, made against the
  real service built for the host, at the example address 192.168.1.20.
- Issue forms, a contact list pointing at the guides and private security
  reporting, and FUNDING.yml.
- CHANGELOG.md dated. CI now publishes this version's section of it as the
  release notes rather than the whole file.
- THIRD_PARTY.md: the DualShock 4 diagram the buttons are drawn after (CC BY
  3.0), and Apollo Save Tool for the package settings.
- Page: the Vibration setting no longer promises to buzz when a game rumbles,
  which 1.0.0 cannot do yet.

.github/workflows/build.yml

@@ -56,4 +56,9 @@ jobs:
         if: startsWith(github.ref, 'refs/tags/v')
         env:
           GH_TOKEN: ${{ github.token }}
-        run: gh release create "${GITHUB_REF#refs/tags/}" artifacts/* --verify-tag --notes-file CHANGELOG.md
+        run: |
+          # The release notes are this version's section of the changelog.
+          version=$(cat VERSION)
+          awk -v head="## $version " 'index($0, head) == 1 { keep = 1; next } /^## / { keep = 0 } keep' CHANGELOG.md > notes.md
+          test -s notes.md || { echo "CHANGELOG.md has no section for $version"; exit 1; }
+          gh release create "${GITHUB_REF#refs/tags/}" artifacts/* --verify-tag --title "Control4Free $version" --notes-file notes.md