Improve README for Self-Signed SSL Environments

[ryanrichter94]

Checklist

• [X] I have verified this is the correct repository for opening this issue.
• [X] I have verified no other issues exist related to my request.

Is Your Feature Request Related To A Problem? Please describe.

• Add a not configured value where the SALT values are listed in the table
• Improve agent install script (last thing on README page) to account for self-signed setup.
• Include Nexus API Key value in table output
• Reorder next steps to 1. agent install 2. internalize packages with jenkins 3. setup computer groups and how to setup/import deployments.

Describe The Solution. Why is it needed?

Some of the fields are empty when using a self-signed setup. As well as other things can be re-ordered for clarity.

Additional Context

Related Issues