doc: Alias skip_while with drop_while

[tesuji]

Many other programming languages use dropwhile instead of skip_while like Rust.

For example:

Language	Name
Python	dropwhile
Ruby	drop_while
Haskell	dropWhile
Java?	dropWhile

[tesuji]

r? @steveklabnik

[steveklabnik]

r? @rust-lang/libs

Sorry, this is not my area of specialty! Someone from the libs team should review this.

[dtolnay]

I don't think doc(alias) works with trait methods. Or it didn't seem to do anything when I built this locally. Can you share a screenshot?

[dtolnay]

r? @dtolnay

[tesuji]

I don't think doc(alias) works with trait methods

Sorry, I overlooked that. cc #50146

Now I use inline doc. But it wouldn't show up when searching.

[dtolnay]

I think I would prefer not to have this kind of content in the standard library docs. Once doc(alias) works on trait methods let's go ahead and use that as originally intended.

[tesuji]

There is pre-existing one for Option::and_then.
My motivation is to save people come from other langauges from
searching Google and other places for "drop_while" function.

I could add a FIXME/TODO to use "doc_alias" feature when it is complete.
But yeah, you may have valid concerns about downside of this.