Add prompt information for zsh completions

[Freed-Wu]

Checklist

• [x] I'm reporting a feature request
• [x] I've verified that I'm running youtube-dl version 2021.12.17
• [x] I've searched the bugtracker for similar feature requests including closed ones

Description

WRITE DESCRIPTION HERE

Now, the completion of youtube-dl is: (e.g. zsh)

❯ youtube-dl --<Tab>
--abort-on-error                 --dump-pages                     --hls-prefer-native              --no-continue                    --rm-cache-dir
...

How about:

❯ youtube-dl --<Tab>
option
--abort-on-error                  Abort downloading of further videos (in the playlist or the command line) if an error occurs
--abort-on-unavailable-fragment   Abort downloading when some fragment is not available
...

It is just

#compdef youtube-dl

compdef _gnu_generic youtube-dl

I believe if use youtube-dl --completion zsh to generate a shell script, it can be done better.

[dirkf]

My expertise only goes as far as https://github.com/zsh-users/zsh-completions, but yt-dl has a GNU-like --help. Although yt-dl has a zsh completion, what happens with this?

compdef _gnu_generic youtube-dl

[Freed-Wu]

compdef _gnu_geneirc XXX is just a fallback solution, it use zsh to parse XXX --help to get a completion, but it is slow than the provided completion script. And it cannot provide higher functions, such as:

❯ youtube-dl --convert-subs <Tab>
selection
ass  lrc  srt  vtt
❯ youtube-dl --proxy <Tab>
URL
file:      ftp://     gopher://  http://    https://