Document new CLI features of 2.1.0

[sgillies]

Namely:

• subscriptions request-pv
• subscriptions request --clip-to-source
• subscriptions results --csv
• orders request --archive-type zip --single-archive
• orders request --delivery

Resolves #985

[sgillies]

Screenshots of new doc sections below. Note that my local mkdocs builds default to night mode.

Orders cloud delivery

Zip archives

Subscription results as CSV

Recommend clipping to source instead of verbose and redundant clipping

[sgillies]

And here is a section about publishing stages and time range types: