cmd/*: add -h/--help options
add license
add readme
To build the server:
$ go build ./cmd/slowping-server
To build the client:
$ go build ./cmd/slowping-client
$ slowping-server -d 2 # delay 2 seconds before responding
...
2022/01/20 00:21:49 got: beep
2022/01/20 00:21:52 got: beep
2022/01/20 00:21:55 got: beep
$ slowping-client -i 1
2022/01/20 00:21:51 got: boop
2022/01/20 00:21:54 got: boop
2022/01/20 00:21:57 got: boop