guide: "Comparing Experiments" improvements

Extracted from https://github.com/iterative/dvc.org/pull/2862#pullrequestreview-781399419 etc.

General

Needs detailed copy editing. E.g. missing “the”, disjointed paragraphs, unnecessary scrolling blocks, etc. (another e.g.)
#3160 ?
Review “baseline” concept. Apply to explanations and branch names? Per https://github.com/iterative/dvc.org/pull/2862#pullrequestreview-781399419
Cover exp show first (exp list later). Per https://github.com/iterative/dvc.org/pull/2862#discussion_r730339949

Specific ideas

Address https://github.com/iterative/dvc.org/pull/2908#pullrequestreview-775523131 .
Cover deps/dependencies column. See #3220
Absorb #list-experiment-names-to-use-in-scripts into #list-experiments-in-the-workspace.
Consider tabs when commands are used as alternatives in specific example tasks (e.g. exp show vs exp diff).
Include/mention --only-changed per https://github.com/iterative/dvc.org/pull/2966 .
Avoid terms “git ref” and “attached”. (Use “based on” for consistency?)
--sort/order-by/no-timestamp sections may be too detailed. Hide or just mention + link to ref.
Merge JSON and CSV sections more somehow (tabs?).
Shorten JSON/CSV output sample blocks and remove corresponding schema descriptions (comprehensive examples are enough). (See https://github.com/iterative/dvc.org/pull/2862#pullrequestreview-783758097 and below.)
Format CSV samples if possible (even if that’s not how they’re output exactly)
Clarify exp diff sections to separate cases: workspace vs. HEAD, rev A vs rev B, etc. (See https://github.com/iterative/dvc.org/pull/2862#pullrequestreview-783894016 and below.)
Distinguish experiments that ran vs queued ones (exo show/list).