httpreplay: fix godoc formatting
Indent so that godoc sets the numbered lists verbatim.
// To record:
// 1. Call NewRecorder to get a Recorder.
// 2. Use its Client method to obtain an HTTP client to use when making API calls.
-// 3. Close the Recorder when you're done. That will save the
-// log of interactions to the file you provided to NewRecorder.
+// 3. Close the Recorder when you're done. That will save the log of interactions
+// to the file you provided to NewRecorder.
//
// To replay:
// 1. Call NewReplayer with the same filename you used to record to get a Replayer.
