Document and test missing keywords

[cromedome]

Unsure what I did on #1587, but this is a cleaner version of that PR. Has all the fixes requested in #1587 with one or two extras.

As with #1587:

• Incorporates the test to ensure all DSL keywords are documented from #1570
• Splits the DSL keywords into a separate document
• Alphabetizes them
• Adds documentation for keywords that have none.

[cromedome]

Merged, thank you. These docs (along with our other docs) could still use improvement, but this is definitely some improvement.