WP-CLI command documentation is not complete

The WP-CLI commands have sparse user-facing documentation, which does not give the user everything they need to know.

For example, the `@synopsis` tag tells me that the `jobs` command has a `status` filter, but not what the valid values for it are. I have to dig through the code to figure out that they're -- as far as I can tell -- `waiting`, `running`, `failed`, and `completed`.

[Adding option descriptions and examples](https://make.wordpress.org/cli/handbook/commands-cookbook/#annotating-with-phpdoc) would result in a much better UX.