Clarify DC/OS Enterprise access control steps

[f5yacobucci]

Step 3 under DC/OS Enterprise of this document f5-ci-docs/docs/marathon/mctlr-authenticate-dcos.rst is unclear.

// Do not include requests for development or report issues with code or products here. This repository contains documentation only.

Bugs

Describe the bug in detail:

• What doc are you reporting an issue with (provide URL)? https://github.com/F5Networks/f5-ci-docs/blob/master/docs/marathon/mctlr-authenticate-dcos.rst
• What information is inaccurate? Step 3 (Define the F5_DC/OS_AUTH_CREDENTIALS JSON blob" doesn't fully describe what to do - after reading this I'm still not sure how to transform or edit the credentials.

This section should be updated and a command documented what should be done here, e.g.) cat $FILE | sed -e ':a;N;$!ba;s/\n/\n/g' -e 's/"/\"/g' (or whatever is correct) as I'm not sure if this is right. The domain expert @edarzins should be able to clarify.

• Is information missing?

• Is a code sample incorrect?

Requests

Provide details regarding what you would like to see added to our documentation:

Environment

• [ ] Cloud Foundry
• [ ] Kubernetes
• [ ] OpenShift
• [ ] Mesos/Marathon)

Use Case

(i.e., what are you trying to do that you can't find documentation for?)

[edarzins]

This is a good place for a complete example, because escaping the quotes and newlines can be tricky.