Permit mnemonics for not just options and subcommands

[EmilyGraceSeville7cf]

To write smth like this:

# prompt

> Change the default DOS style prompt in a command window
> Help: /?
> More information: https://learn.microsoft.com/windows-server/administration/windows-commands/prompt

- Reset a prompt to the default one:

`prompt`

- Set a specific prompt:

`prompt {string prompt: $d $p$g}`

- Set a prompt to show the current [d]ate first:

`prompt $d $p$g`

- Set a prompt to show the current [t]ime first:

`prompt $t $p$g`