Make link to processing info doc more prominent

[cbethell]

Issue Addressed
Closes #238

What is the purpose of these changes?

Per #238, the existence of the processing-information.md file is not obvious in the way we link to the documentation in the headers of the workflow steps. This PR tries to make linking to the processing info documentation more prominent.

What changes did you make?

This PR fixes the existing links to the processing-information.md file (now that we moved it into the subfolder additional-docs) and adds a couple additional mentions of the documentation itself in the effort to make its existence a bit more obvious to users.

Any comments, concerns, or questions important for reviewers

• Does this PR seem to adequately address issue Make link to processing information more prominent  #238? Are there any other places in the README that would benefit from having the processing information doc mentioned and linked?

Checklist

Place an x in all boxes that you have completed.

• I have run the most recent version of the code
• If I am adding in reports or generating any plots, I have reviewed the necessary reports
• I have added all necessary documentation (if applicable)

[allyhawkins]

This generally looks good, just a comment on how to make the link even more obvious.

[cbethell]

I added that button as you suggested @allyhawkins, good call! Let me know what you think of things now 👍

[allyhawkins]

Looks good, just one more suggestion, but I don't need to see it again.