Revisit unused tutorials pages

[etrapnell-nist]

There are a few tutorial docs pages that are in an intermediate state and aren't currently referenced by any sphinx tables of contents:

• tutorials/essential_workflows/part-0.rst
• tutorials/essential_workflows/part-1.rst
• tutorials/essential_workflows/part-4.rst

[colton-lapp]

I forgot to clean some of these up, but i.i.r.c.:

• part-0 and part-1 were essentially the hello-world tutorial, but in a data science context, so those could be deleted
• part-4 was trying to implement metrics, but that feature wasn't ready. At some point metrics could be incorporated into the tutorials when that feature is more developed but I'm skeptical the usage in part-4 is the best way, but might be worth keeping it for reference as a starting point once metric functionality is further developed