Update configuration.md

[jenworthington]

I'm not actually done with this one yet, but it's very long and I am at a stopping point, so creating the pull request now to save the changes I have made. :)

[mstopa-splunk]

@jenworthington all right please let me know when I should do my pass on it

[jenworthington]

Sorry I thought I had already sent it as ready for review. You can review this now.