chore: add service csb command

[pivotal-marcela-campo]

##182651749

Checklist:

* [ ] Have you added or updated tests to validate the changed functionality?
* [ ] Have you added Release Notes in the docs repositories?

• Have you followed the Conventional Commits specification?

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/186435122

The labels on this github issue will be updated when the story is started.

[blgm]

Would you mind adding it to the docs here: https://github.com/cloudfoundry/cloud-service-broker#local-mimic-commands

[pivotal-marcela-campo]

Would you mind adding it to the docs here: https://github.com/cloudfoundry/cloud-service-broker#local-mimic-commands

Will add in a different PR, there are a few commands missing in the docs. Thanks for pointing that out.