Document array-accepting manipulation methods

Note: I have not built the site with these changes in order to visually verify them.

> Unit tests which assert this behavior:
> 
> - append:
>  https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L291
> - appendTo:
>   https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L506
> - prepend:
>   https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L607
> - prependTo:
>   https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L671
> - before:
>   https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L739
> - after:
>   https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L291
> - insertBefore:
>   https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L784
> - insertAfter:
>   https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L853
> - replaceWith:
  https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L988
> - replaceAll:
>   https://github.com/jquery/jquery/blob/410cf4ee6bd454fa7e2bb5dc37a0b051f15d3e96/test/unit/manipulation.js#L1031