Define CLI option descriptions consistently

[ashmaroli]

Summary

• List options with default values after ones that do not.
• Terminate sentences with a period.
• Mention default values with a consistent pattern (default: ...), at the end of description.
• Use double-quotes to delimit strings, optionally single-quotes for substrings.
• Align parameters for better readability for humans (opinionated.).

[parkr]

I haven't looked through these yet but I was thinking that we could auto-generate the documentation from these options somehow (in a separate PR). Thanks for cleaning these up!

[ashmaroli]

I was thinking that we could auto-generate the documentation from these options

Yes, we could. I have already developed a vision / idea locally.
I found current docs theme off-putting so came up with my own opinionated design to suit the local development.

[parkr]

@jekyllbot: merge +docs