Vec::insert docs are wrong about panic condition

[Arnavion]

rust/src/liballoc/vec.rs

Lines 716 to 718 in f0e5c95

	/// # Panics
	///
	/// Panics if `index` is out of bounds.

In fact, as the second example shows, index == len is allowed. The phrase "out of bounds" is used in the docs of other methods (remove and swap_remove) to mean 0 <= index < len so it should not be used to mean 0 <= index <= len here.

Suggest changing the wording to match Vec::split_off :

Panics if index > len.

[frewsxcv]

thanks for pointing this out! i just opened a pull request #47121