- Provide some documentation
- Make cmake keywards and sctp lib name lowercase
- Use standard form of find_package_handle_standard_args()
- Make an imported target sctp::sctp that will fail if being used in
cmake unless defined, which will avoid that "sctp" appears in the
cmake code but is silently discarded
See also:
https://cmake.org/cmake/help/latest/manual/cmake-developer.7.html#a-sample-find-module
