Rationalize samples

[craigbox]

$ rg bookinfo --glob '*.md' --files-with-matches | wc -l
      60
$ rg sleep --glob '*.md' --files-with-matches | wc -l
      61
$ rg notsleep --glob '*.md' --files-with-matches | wc -l
       2
$ rg httpbin --glob '*.md' --files-with-matches | wc -l
      40
$ rg helloworld --glob '*.md' --files-with-matches | wc -l
      35

(The fact our curl client container is called sleep has always perplexed me.)

I would like the docs to be able use one sample deployment throughout. Could we please have an (optional) add-on for Bookinfo that includes a pod called "client" and a pod called "server", where client is curl and server is httpbin, if that's still the gold standard?

(httpbin is unmaintained - consider https://github.com/mccutchen/go-httpbin / https://hub.docker.com/r/mccutchen/go-httpbin)