maint: update NEWS.
Closes
* NEWS.md (New features): Mention new getsockopt binding.
based `build-aux/luke` and `lukefile` describing how to compile and
install everything. Building with LuaRocks now leverages this too.
- - New `posix.sys.socket.getpeername` binding.
+ - New `posix.sys.socket.getsockopt` and `posix.sys.socket.getpeername`
+ bindings.
- New `posix.sys.msg.msgctl` binding, and `posix.sys.msg.IPC_RMID`,
`posix.sys.msg.IPC_SET` and `posix.sys.msg.IPC_STAT` constants to
