[NO ISSUE] Updated out-of-date information in README
[NO ISSUE] Updated out-of-date information in README

- user model changes: no
- storage format changes: no
- interface changes: no

Details:
- Updated the path of start-sample-cluster.sh in README

Change-Id: If8a4884c0a59ded2388416bfca3359108a19f67a
Reviewed-on: https://asterix-gerrit.ics.uci.edu/3114
Reviewed-by: Michael Blow <3f64e033f015f10d416a166dcd735dbc31e7ff2a@apache.org>
Tested-by: Michael Blow <3f64e033f015f10d416a166dcd735dbc31e7ff2a@apache.org>
Contrib: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@fulliautomatix.ics.uci.edu>
Reviewed-by: Ian Maxon <75f98fe183e5455573e3e67a0344be46e7dea75a@apache.org>

apache/incubator-asterixdb,apache/incubator-asterixdb,ecarm002/incubator-asterixdb,apache/incubator-asterixdb,ecarm002/incubator-asterixdb,apache/incubator-asterixdb,ecarm002/incubator-asterixdb,apache/incubator-asterixdb,ecarm002/incubator-asterixdb,apache/incubator-asterixdb,ecarm002/incubator-asterixdb,apache/incubator-asterixdb,ecarm002/incubator-asterixdb,ecarm002/incubator-asterixdb