Add a LICENSE file to the repository root

[parasew]

OONF's source files carry BSD-3-Clause headers, but the repository has no standalone LICENSE or COPYING file at the root.

This causes practical problems downstream. I'm reinstating the oonf-olsrd2 package in the OpenWrt routing feed (openwrt/routing#1176), and OpenWrt's packaging conventions require a PKG_LICENSE_FILES parameter pointing at the upstream license file. With no such file, there is nothing to reference.

The same issue affects license scanners, SBOM tooling (SPDX/CycloneDX), and distribution packaging generally, all of which look for a root-level license file rather than parsing per-file headers.

Would you consider adding a LICENSE file at the repository root containing the BSD-3-Clause text as used in the source headers? Optionally, adding "SPDX-License-Identifier: BSD-3-Clause" to source files would also help automated tooling.

Happy to open a PR with the LICENSE file if that's useful.

[mathiashro]

Dear @parasew - sure, kindly go ahead creating a PR. We should use BSD-3-Clause at this was the original intention of the authors. We can have a review with the team here once your kind PR has been received.