[Finish #121957927]
[Finish #121957927]

  - Update README to include cli usage information

Signed-off-by: Jesse Malone <c929decda31f28e677c5c623b33cb23472ce0fde@pivotal.io>
Signed-off-by: Tony Wong <3261da024e85c36767bb9324ced93ba4333a2c77@pivotal.io>

pivotal-cf/cred-alert,pivotal-cf/cred-alert