[docs] Add clarifying example of `fn` param to option()

[gregfenton]

The description for what the fn parameter of option() is sparse and there are no examples of its use. Looking at the code for it, the use is non-obvious.

[gregfenton]

Might also consider adding an example of a parameter being passed that is quoted:

$ node options-common.js --pizza-type='veggie lovers' -s

pizza details:
- small pizza size
- veggie lovers

See the Options docs and the options-common.js examples.

[shadowspawn]

See the README section on custom option processing:

https://github.com/tj/commander.js#custom-option-processing

[gregfenton]

Okay, cool that it is in there. But it was not obvious to see/find. It comes after a long scroll and after topics labelled "Other" and "Misc"....at which point I assumed I had hit the end of the Options section.

Feel free to close as the docs are there. But I recommend some sort of tweaking to make this more obvious. I did not link the fn parameter to be "custom processing".

[shadowspawn]

For context, why were you looking for more about the fn parameter? From in-editor assistance while typing, or looking at the Javascript code, or looking at the TypeScript definition?

[gregfenton]

In-editor (VSCode). I was looking to do something new but realized that I didn't have sufficient information to know what fn did, or whether it could be a valid approach. Ultimately chose to do something different, but that was after some frustration trying to understand fn.

Again, delighted that the docs are there. But didn't find those docs on my own.

Thanks!

[shadowspawn]

Related, someone who "didn't notice the ability to pass in a processing function": #1953

[MaxumCSmith]

Thank you.

[shadowspawn]

Opened #2009 with a rework of the inline documentation. Single most relevant change was renaming fn to parseArg!

[shadowspawn]

Shipped in Commander v11.1.0