Release Jarl under the MIT License

LICENSE is installed with the docs, included in make dist, and becomes
the Debian package's copyright file together with the bundled Cinzel
font's OFL.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -24,6 +24,9 @@ The first version, to be released as 0.1.0.
   the web UI. Networks smaller than a /24 explain that they belong in the
   enclosing /24's zone.
 - docs/operations.md: setting up a secondary server with its own jarld.
+- Jarl is released under the MIT License (`LICENSE`), which is installed
+  with the docs and is the Debian package's `copyright` file (with the
+  bundled Cinzel font's OFL).
 - A Debian package: `make deb` builds `dist/jarl_<version>_<arch>.deb` with
   only `dpkg-deb` (no root), for the host or any other architecture
   (`DEB_ARCH=arm64`). Installing it creates the `jarl` user and directories